The floating captains are getting €222.5/hr (- 4.50 sim). If they are LTCs, they get €15 extra per hour. If they happen to be a TRE then it's another €15 extra per hr.
Floating FOs are getting €133/hr.
Fixed base contractors get the above figures minus €50/hr (no floating supplement). I've flown with floating captains this summer already so it wouldn't be new. The company are genuinely short though, there literally are not enough based captains to cover the schedule.
As for HMRC, I know of pilots who they were very interested in and are now getting audited. They took home ridiculous pay checks though.