I havn't gone through a similar experience, but the advice i can give is photocopy every single page in your log book if you do decide to go ahead with it. Might be a bit expensive, but surely it's better than having no records whatsoever. At least you're partially covered then. Perhaps you could also get an examinor (or someone else of similar 'high standing' within the caa) to certify the hours in your log book as well. Again if you loose it you have something to fall back on.