I went back to the gym after my son was 4 weeks old. GoodLife has a childminding program were they will watch your kid for up to 2 hours, working out avidly and eating well was already in me so it wasnt difficult to get back into the routine, I think if its already in you, you can go back into it more smoothly.. The classes are great and I shower , use the sauna, blowdry my hair for the other hour afterwards in peace and quiet with no interruptions, its awesome!
Needless to say, I've always been on the run -mad dash getting things done as efficiently as possible kind of person so being organized helps alot.