Don't know if allowed to name firms but having spent 6 hours on web and phone I located an incredibly thorough insurer who was willing to offer insurance for Europe wide travel even though I am currently on iv FCR. They asked about all medications and seemed to understand CLL. It's called World First. Obviously not had to claim, but the fact that I have travel insurance has really raised my mood! It took about 45 minutes and they needed WBC levels and other blood results information as well as dates of hospital visits.
On cycle 5 of FCR As part of FLAIR trial. Hope this helps someone else in the UK. Incidentally they changed rule on iv only last week, so if you tried before, try again...
The insurance was annual! It was affordable! The one off trip I planned for has now morphed into several short European trips once FCR over! I am very cautious and take extreme care with bugs. Good luck fellow travellers!