I worked for them for two years out of LHR. Money is good. Trips are also good. In average you do three to four trips, six to eight sectors, a month. LHR crew go to both CDG and FRA. The crew can be a bit difficult (sometimes they won't even speak to you) and they make you work extremely hard. When they ask you to check the toilets, that also means to clean them!
Training is done in both London and Tokyo and nearly two months long. They teach you Japanese and you must know all the drills in that language!
Either you will love it or hate it. Good luck!