I just had my first rostered weekend off in 6 months (apart from the weekends associated with annual leave). Don't expect too many weekends as the AIMS rule giving 1 in 4 weekends off is a "soft" rule.
As stated, expect to spend a lot of time looking out the hotel room window at the Bath Road. 4 in a row of 11 hour plus, (the late dual Hannover) can be a little tiring, but that should be a fairly scarce thing if the Crew Council ever manage to corner the crewing manager!
That's the downside. The upside is I've flown with some great people, gone to some interesting places, with the prospect of an even more interesting year ahead. If you can cope with the workload of MAN-LHR you can cope with anything, our company engineering support is pretty good and if you opt for LHR posting, management seem to forget you exist!