Dont do it to yourself. You will not only lose your sanity, but also your general life away from work.
I f you want to work 6 days on 2 days off all year round, 6 sector 2 day trips to spain and portugal with 10 hours in a crap,stuck in the middle of nowhere (portugal) hotels for £80, its upto you.
I would do charter, much more fun,,chance of long haul maybe, and if you dont like it,its only a temp contract.
The only good thing about GB are the crews, nearly everyone hates it so you can at least have a laugh about how s*** it all is.