I'm not sure why it would become UKIP under PR. In the first place a purely proportional system would do away with constituencies altogether, so in that sense Folkestone and Hythe would lose its individual representation. Your 22% of voters who voted UKIP would help to go towards a UKIP MP though. It just wouldn't be your MP in particular.
I think it is important to support political reform not because of the particular result it might give but because it is intrinsically fairer. If a proportional system gives UKIP more influence this is only because they have enough voters supporting them to give them those seats (I think they would have got at least 50 MPs, if not 60, under pure PR). Equally, one of First Past The Post's strengths is absolutely not that it shuts out a party you don't like -- while it may suit some that the Labour party and Conservatives tend to win the maority of MPs, those ~15% of people who voted for the Green Party or UKIP have ended up with 2 MPs for their troubles. This is unfair even if you don't like those parties.
Political reform is then about making things fairer for as many people as possible. If they then vote for parties you don't like, the message is that you need to work harder to win the argument. One of the things FPTP does is lower the number of voters a party needs to win a majority to roughly 1/3 as opposed to 1/2 (after removing those who don't vote).
Long story short: you should support or reject a system because it is fairer, or not, rather than because of who it lets in or keeps out of parliament.