Not worth a lot because the legal system is different in the UK so you can't win the massive payouts you can in the US (and so the bids can't go nearly that high). One site (that's paying to advertise prominently in Google UK) claims to be able to recover up to 65,000 pounds (about $110,000) where the disease was very severe and lead to premature death or disability. Given that they're going to make the best sales pitch they can, it shows the huge gap between the UK and US judicial systems (looks like the range is $750,000 to $2,500,000 or more in the US for similar injuries).
Couple that with the fact that lawyers are not attorneys, and mesothelioma is very commonly known as asbestosis, and the value's really hit.