Switch,
If you are at either of the Integrated training providers in the UK, both have Rotary Training departments that will be more than happy to provide you with all the details. Don't worry, 'fling-wingers' don't bite...
(And I'm presuming that you've got a 'Frozen' ATPL (200hrs-ish) at the moment, rather than a full ATPL (1500hrs-ish)...)
Although, in brief:
Exams: Yes, only 1 more exam at the moment (although this is in the process of changing...) Not sure on the time validity though - check with your groundschool.
Flying: 135hrs (of which I think that you get roughly 20hrs 'credit' for your fixed-wing time. Check LASORS for details.) And remember that you're looking at roughly £2-300per hour for a basic piston trainer. If you want a fATPL(H), you'll have to convert your IR(A) - according to LASORS, a
min of 10hrs IR training in a heli plus flight test and skill test. ie 15hrs @ £6-950per hour. I'll let you do the maths...
Jobs: The prospects at the moment aren't any brighter than for our fixed-wing brethren. If anything, they're worse. If you want to use your IR, then the North Sea is your only realistic option (and the operators up there probably won't be hiring for at least another year or so). If you want to instruct, you need a min 300hrs helicopter time (no credit for fixed-wing time). Once again, I'll let you do the maths on that one...
And after all that, is it really worth it? Well, before I started, somebody once described flying a heli to me as 'the most fun you can have with your clothes on'. I whole heartedly agree...
Safe flying,
B73