FLR-duty hours
I suspect that one of the reasons that your query isn't being answered directly-or promptly-is because nobody really knows.
For a shorthaul trip LHR-AMS-LHR duty hours will be flight time+ ~a couple of hours. From my previous example LHR-JFK-LHR, a 3 calendar day trip away from base for 48 hours, again ACTUAL duty hours will be flight time + a few hours. Same duty hours if it's a 5 day trip with 92 hours away from base, but you will be compensated/won't be penalised for being away from home longer.
Ad hoc ground duties (great definition-wish I'd thought of that), typically a sim duty will be ~6-8 actual/real/duty hours for which you'll get 4.5 hours credit. A whole day doing SEP/medical will be longer real/duty hours but the same credit. 12 hours of standby duty-4.5 hours of credit, and so on. It will still bugger up pretty much your whole day whichever way you cut it so people tend to look at how much each trip/duty will contribute towards the total monthly needed rather than duty hours. I'm sure there's a weekly/monthly/yearly never to exceed duty hour total but I've no idea what that is-somebody on here must know.
Real flying hours count 1 for1 so the secret would be to go for everything that is a quick out and back, live in Stanwell, go to work on a pushbike and simply chain it to a trolley at T5. Now...count up the extra non duty hours going back and forth to work in your time and you can perhaps see the benefit of doing a few nightstops and getting your bar bill paid by the company (Allowances are paid for each/every trip at £X.XX p/h base to base or similar~reasonable wonga per 24 hour day) and getting the extra credit (see JFK example in previous post) added to your monthly accrual, with just one trip to T5.
I'm not really up to speed on the way the current bidline works, but people seem to think that in S/H you'll do ~18-23 days work, (or more correctly days in which work intrudes into your life at some point) and maybe slightly less in L/H. I stand to be corrected on this, but remember this is all ruled by seniority. The great thing about bidline is that some soppy roster clerk can't just add standbys to your roster cos he's had a missive from on high/doesn't like crew that you have to work 23/31 when there's no actual work uncovered.
So in answer your question-how many duty hours in a year? No idea.
S