If you are lucky: £20,000 + Benefits.
If you frelance: £100 - £140 (incl benefits) per day
If your not lucky or just on average salaray: £15,000 - £20,000 INCL Benefits
It depends on the employer, the contracts they fly, how many hours you will fly and your experience.
If they ask you in an interview, push for the low twenties. If you are good enough you will get it!
OSOP