Lots of my friends with new babies have been to Centre Parcs. You can hire a chalet (and even take the in-laws along if you want). It's self catering but there's lots of places to eat on site, Mrs J can get pampered there if she wants, and there's loads of activities to do - including a heated pool that the little one might enjoy.
Off peak it's not too expensive (if you go midweek) - and they often offer discounts too.


