Hi,.
My best advice is to make a backup of your owned music.
Any music you added from Apple Music you have to write down or take screenshots of them.
Then proceed as told by Apple and cancel your subscription for Apple Music for the Ukrainian store. Change your location to the UK and subscribe again to Apple Music.
Your own music will be matched or uploaded back according to the UK Apple Music database.
Now add those songs you had previously added from Apple Music to your library and you're all set.
Please keep in mind that not all songs available in the Ukraine will also be available in the UK. This will result in songs matched in the Ukraine will now be uploaded. Or songs previously uploaded in Ukraine will now be matched.
Same goes for songs added from Apple Music.
Not all songs in the Ukraine will be available in the UK. You will have to buy those songs from the Ukrainian iTunes Store. That's why I recommend you to just make a new account for the Ukraine after switching to the UK in your currently existing account.
If you have any further questions, please join our forum. We're happy to help.