Get a referral to your nearest Vet School - there's one in Bristol.
They will have access to all the latest technology and be up-to-date with the latest techniques. If you are covered by insurance, now is the time to get this done.
Make sure you never change insurers after this though - it will be a pre-existing condition and will not be covered by a new insurer. Also check what sort of cover you have. Some won't payout in the future if you don't make a claim within a certain period after diagnosis. Also, some policies only cover illness for the first 12 months, others offer cover for the life of the animal. So, do check your cover first.
Sue