First:

Repetition of ‘Umrah for the Muslim in one journey, either for himself or on behalf of someone else, is not from the Sunnah of the Prophet (may Allah’s peace and blessings be upon him) nor his Companions (may Allah be pleased with them) nor was it from the guidance of the pious predecessors. The basic principle is that for each ‘Umrah there is a separate journey.

Ibn al-Qayyim (may Allah have mercy on him) said in Zaad al Ma’aad (2/ 89-90): 

“None of his (may Allah’s peace and blessings be upon him) ‘Umrahs were performed by leaving Makkah as many people do today. Rather, all his ‘Umrahs were done while entering Makkah. He remained in Makkah for thirteen years after the revelation was first sent down and it has not been reported that he did ‘Umrah by leaving Makkah during that time.  

The ‘Umrah which the Messenger of Allah (may Allah’s peace and blessings be upon him) performed and prescribed was the ‘Umrah for one entering Makkah, not the the ‘Umrah of one who is already in Makkah, then leaves the “sanctuary” to return for an ‘Umrah. In his time, only A’ishah did this and it was due to a specific situation; that is, she had the intention of performing ‘Umrah, but her menses occurred. The Messenger of Allah ordered her to do the Hajj with ‘Umrah, and thus she performed Hajj Qiran (a type of Hajj where Hajj and ‘Umrah are done with one ihram). 

He informed her that the tawaf (circumambulation) around the House and walking between Safa and Marwah counted for both the Hajj and ‘Umrah. 

However, she felt somewhat upset that her friends (other women) would return having performed Hajj and ‘Umrah separately, as they performed Hajj Tamattu’ and did not menstruate during that time; whereas A’ishah performed Hajj Qiran and her ‘Umrah was included within her Hajj. 

The Messenger of Allah then ordered A’ishah’s brother to take her out to Tan’eem, and return to Makkah in order to perform her ‘Umrah and to make her feel better. 

However, he did not perform ‘Umrah from at-Tan’eem during that Hajj not did anyone else who was with him.” End quote 

Second: 

The majority of scholars have allowed one who performs ‘Umrah to perform another one during the same journey, especially if he is from outside Makkah and it is a long journey and difficult to return once more. In that case, he has to leave to the nearest place outside the “sanctuary” in order to get into ihram for the other ‘Umrah. 

Al-Bukhari (1215) and Muslim (1211) report from ‘Aishah (may Allah be pleased with her) that she said: “O Messenger of Allah, you did ‘Umrah and I did not. He said: O Abdur-Rahman, take your sister and make her perform the ‘Umrah from at-Tan’eem. So he took her on his camel and she performed the ‘Umrah.” 

In another narration found in Bukhari and Muslim, the Prophet (may Allah’s peace and blessings be upon him) said to Abdur-Rahman: “Leave the sanctuary with your sister and let her intend ‘Umrah.” 

Al-Imam an-Nawawi said in his commentary on Sahih Muslim (8/ 210): 

“’Leave the sanctuary with your sister and let her intend ‘Umrah’ in this is evidence for what the scholars said: That one who is in Makkah and wants to perform ‘Umrah, then his meeqat (boundary) for it is the closest area outside the sanctuary and it is not allowed for him to don the ihram within the sanctuary (haram). The scholars said: It is incumbent to leave the sanctuary so as to combine between the area outside the sanctuary and the sanctuary as the pilgrim does, for he stands in ‘Arafah (which is outside the sanctuary), then enters Makkah for the tawaf (circumambulation) and other acts. 

These are the details of the Shafi’ee school of thought, and similar to this has been said by the majority of scholars: That it is necessary to leave to the closest area outside the sanctuary to don the ihram for ‘Umrah, and if he were to do so from within the sanctuary and not leave, a penalty (sacrifice) would be binding. ‘Ata said: There is nothing on him (i.e. no penalty). 

Malik said: It will not count until he leaves the sanctuary. Al-Qadhi ‘Iyadh said: and Malik said: He must don the ihram from at-Tan’eem specifically. They said: It is the meeqat (boundary) for those performing ‘Umrah from Makkah. But this is an isolated and rejected opinion for the majority of scholars opine that all areas outside the sanctuary (in any direction) are equal; at-Tan’eem is not specified.” End quote. 

Al-Imam Malik said in al-Muwatta (1/ 282): 

“As for ‘Umrah from at-Tan’eem, then whoever wants to leave the sanctuary and don the ihram, then this is sufficient for him Insha Alah, but the virtue is to intend (‘Umrah) from the boundary set by the Messenger of Allah (may Allah’s peace and blessings be upon him) or from that which is further than at-Tan’eem.” End quote. 

Al-Imam ash-Shafi’ee said in al-Um (2/ 133): 

“The boundary for ‘Umrah for one who is in Makkah is the area outside the sanctuary, and it is better to don the ihram from Ji’irranah or at-Tan’eem”. End quote 

Ibn Qudama said in al-Mughni (3/ 246): 

“If the people of Makkah want to do ‘Umrah, then it must be from outside the sanctuary. But if they want to do Hajj, then it is from Makkah. The people of Makkah or those in Makkah are equal in that, whether they are travelers or resident because whoever crosses a boundary, that is a boundary for him and whoever is in Makkah then it is his meeqat for Hajj. If he wants to do ‘Umrah, it must be from outside the sanctuary and we know of no difference of opinion in that. That is why the Prophet (may Allah’s peace and blessings be upon him)ordered ‘Abdur-Rahman to make ‘Aishah do the ‘Umrah from at-Tan’eem.” End quote 

Sh. ‘Abdul ‘Aziz ibn Baz was asked: If someone comes to Makkah for Hajj or ‘Umrah, then is it permissible for him after that to perform another ‘Umrah for himself or on behalf of another during the very same season he came in such that he leaves Makkah to at-Tan’eem for ihram and then performs the ‘Umrah? 

He (may Allah have on him) responded: “There is no harm in that, all praise is for Allah, if he came for Hajj or ‘Umrah and performed them on his own behalf or on behalf of someone else and then wanted to perform another ‘Umrah for himself or on behalf of someone else.There is no problem in that, but one must go outside the sanctuary for it; he must go outside the sanctuary of Makkah, at-Tan’eem or Ji’irranah or somewhere else and don the ihram from there, then enter (Makkah) and do the tawaf, walk between as-Safa and al-Marwah and shorten the hair.This is allowed whether it be for himself, a deceased relative or friend or one who is incapable, such as the elderly… there is no harm in that.’Aishah did this upon the instruction of the Prophet (may the peace and blessings of Allah be upon him), as she did ‘Umrah with the Prophet, then on the night of the 13th she took permission to do ‘Umrah and he permitted her, ordering ‘Abdur0Rahman ibn Abu Bakr (her brother) to take her to at-Tan’eem and then perform ‘Umrah. This is considered a seconf ‘Umrah from within Makkah. 

So in conclusion, there is no harm in one performing ‘Umrah or Hajj for himself then performing ‘Umrah on behalf on someone else as it is also allowed to perform Hajj or ‘Umrah on someone else’s behalf then perform ‘Umrah for one’s own self. There is no harm in that.” End quote 

http://www.binbaz.org.sa/mat/18832

Based on that, If you were to come from the UK and perform ‘Umrah for yourself, then you wanted to do ‘Umrah on behalf of your deceased father, you need to leave the sanctuary (and at-Tan’eem is closest), don the ihram there and then return to Makkah to perform ‘Umrah on behalf of the deceased. 

It is not necessary to change the clothes of ihram which you used, but rather it is allowed for you to wear any permissible clothing of ihram. It is preferred that the ihram clothing be clean and white.

For further information you may see answer number 109341.

And Allah knows best.