Silly question, but why does it have to be UK based ? UK insurance companies tend to be more expensive than Continental European ones. Premiums I've seen here range from 0.25% to 0.40% p.a. for death & work disability insurance.
Brokers accept PPL's without any fuss. You need a valid PPL & Medical. Some exclusions for over water flying (except channel crossings) and the usual stuff about forecast extreme weather apply.
PM me if you want the name and contact details.
Disclaimer : I do have a conflict of interest in this matter, in that the insurance broker sponsors my flying club.