I can only speak from experience:
Haywards Aviation Insurance London, are who I am insured with and they have been tested in anger on 2 occasions with our pilots here. On each occasion they were true to their word and very efficient.
Expect around the £2000/yr premium for £200,000 cover. It all depends on your job and age.
Whatever you do, READ THE
small PRINT!!!
It is VERY important to understand the following:
When/If the CAA pull your licence, they do so for the duration of any investigations. The licence is then said to be suspended.
Only in a very few cases (literally miniscule)do they then downgrade you further where they permanently remove your licence. In 99.9999% of the cases they 'suspend' your licence forever, because there is a tiny chance you could get it back.
You might still be able to fly 'multi crew' which in the Uk basically means you've got to go to the offshore guys and ask for a job!!!
If your licence is suspended, then you DON'T qualify for LOSS of licence
You need to insure for LOSS OF YOUR CURRENT POSITION. I.e single pilot IFR, or single pilot helicopters, etc and get it sanctioned by the insurance company.
There are an awful lot of commercial pilots out there who think they have LOL insurance when technically...they don't!