Is going to a gym financially viable for you? Most have a creche so you can go at any time.

My DH truly understands that if I don't exercise I can be a right cow - so if it means he does the bath / bed routines with both kids, he'd do it. Before I started to shed the kg's he saw I was down, and quite negative about myself. Now I exercise and have lost weight he see's how much more vibrant I am now - so it's in his best interests (aint mumma happy - ain't nobody happy ).

In saying that I can get DD and DS down for a nap at the same time. They're both in bed at 8pm - 8.30pm, so if I really feel the need for more exercise I'll do more then too (mainly when DH is on arvo shift at work and not home though).

To cut down on the evening routine maybe try a slow cooker so all you (or DH) need to do is serve dinner in the evening as opposed to making it.