I am from Norfolk. They have gay people there, more than one per village in fact! But, you would be a bit more of a novelty than a gay guy in London, Brighton or Manchester.
Would you consider looking for a gay only flatshare instead? That way your friend could have the distance that he is looking for while seeing you regularly, while you could make some friends you share some interests with and be less reliant on him. If it is impractical to find somewhere before you move there, you could stay with him and find some innocuous reason you need to move out after a couple of weeks. For example, distance to work, price, something about the room.
The idea of you getting a girlfriend is very silly for everybody concerned, especially for this girl who would probably be very miserable in a relationship with someone who didn't fancy her!
Hope this was some use to you. Good luck resolving this sticky situation.