nip and tuck as far as i am aware is a sky one series and at the moment that is one of the channels that was withdrawn a while ago except for if you have sky , but looking around , Season two will begin on Channel 4 on Wednesday 8 June, 10.50pm
Well I don't watch the show and I'm on cable so I don't get Sky One anymore but from what I can find out, it seems Series 4 started on Sky One on the 8th of January 2007.
It seems the last episode in the series (episode 15) is being shown this Saturday (28th) on Sky One at 23:00. The following link may be of some use: