blackbear 1
Just as an addendum to Alex's above.
I left in 2000 with 3000hrs Sea King/Lynx and went straight to Britannia (sic) 757/767. Then LHS with Thomson 737 since 2005. The general attitude of the CAA at the time was helpful and if you told them where you are and where you want to be, they were very obliging on issuing a road map on how to get there. The single most important point I remember was get an ATPL(H) or a CPL(H) - but take the ATPL(A) Nav exams! - not only did it give you a fall back licence for employment but I also got a letter from the licensing department stating that the exam passes remained valid for the entire validity of the professional licence - you never know, plans change....