This thread is fascinating and very reassuring.
Hatwoman, I have a similar feeling with being out of London. I can still carry on freelancing out of London, but it's not the same as really all meetings and information gathering need to be done in London. So I end up doing the scraps of work that could be done anywhere with internet and a laptop, but they're not really the interesting scraps.
I dream of going to evening events and receptions at Downing Street and expensive art galleries like I used to with my work. I do miss the freedom and excitement of dressing up and having an identity that can be quantified and appreciated -not just "mummywhotellssmallchildrentobrushyourteethyesnowplease!".
I am relatively lucky in that DH looks after DD3 and does the school run once a week which means that I have a day to go to meetings etc. Maybe I need to start doing that more.
I think you work from home? That's also particulary isolating, even if you're working on interesting material you're still looking at the dishwasher etc - you're still surrounded by the trappings of domesticity.
Much as I love my children I do miss the old me. I guess that's a fairly common phenomemen with women having children later having established their careers.
I do have strange thoughts of having another child because it gets me out of the whole "where is my career going now DD3 can be left with childminder and I have the opportunity to face up to my career but don't know how to". I read a rather depressing book at my mum's called "The Cinderella Complex" that said how many women had another child because it was easier than facing up to career questions!