Yep, I ran that through a take home pay calculator. Basic tax code of ten grand and called it 78k pa. A take home of £4380 plus about 500-600 on per diem after that's taxed if you're lucky. No pension paid so you'd have to take a fairly sizable chunk out of that to make up lack of company pension with a private fund. Say you wipe off 500 quid towards a pension. That leaves you with £3880 in your pocket plus the per diems.
Oh and 25 days leave of course. For a long haul Captain rewarded by crappy hotels and min rest night stops.