The £170 and other expenses associated with travelling down might seem like a total annoyance and unfair to some; but if you really are that set on becoming an airline pilot and your heart is really in it, and you really want to be a part of CTC, definitely have another go at it.
If you pass, great - it was worth it! And if you make it all the way, believe me, that £170 or so is going to seem like a drop in the ocean compared to the £60k bond, £600+ insurance, £5000+ foundation course fee and (in my case anyway)the prospect of having to pay off your student loan from university on top of it all!
If you don't pass - of course, you're going to feel aggrieved at having blown another 170 notes. But if you really are dead set on entering the industry, and given CTC's reputation and employment prospects, would you have been prepared to give up and go through life thinking "what if?" It's an expensive "what if", but when you consider what might be if you then turn out to be successful - and also factor in what you might earn elsewhere if you're not - I'd say it's well worth it.
Go for it, and best of luck.