2 nights 2 days cannot work as that would mean a 24 hour shift in the middle...
i am working a general 2 days 2 nights shift pattern with a few changes here and there, but never going over the 14/15/16 shifts a month...
For my personal preference the finishing at 0700 on my first day off is perfectly acceptable, its weighed off against the 24 hours between my day and night shift...
As for the annual leave allowance, my 18 days are plenty (plus BH lieu days if i choose to take), i'm currently a week into 3 weeks off, and i used 6 days AL for that...
so for me, 2days 2 nights 4off, best shift pattern there is!
cheers,
buzzz