Plenty of threads on here which cover your query. I'll let someone else post the links. However to summarise, pay is good and on a par with the European majors.
The pension for new joiners is poor, verging on pathetic.
On shorthaul, you will work 750-800 hours per year, depending which fleet you are on.
On longhaul, you are contracted for 900 hours per year which many people achieve.
All fleets, apart from 737 LGW, use Bidline which is a seniority based system. ie. The most senior guy does as he wants, the most junior does as he's told. As a junior, you will get a Blind Line (which means effectively that you are rostered) and will work most (all) weekends. On shorthaul, you will probably do long tours. On longhaul, you will do short two-crew trips.
Command time for a new joiner is 12-13 years for LGW shorthaul, 14-15 years for LHR shorthaul, 19+ for LHR longhaul.