Reading through the thread "Going back to work" took me back to when I was returning and the obstacles I faced 10 years ago don't seem to have changed! I was a single mum to 2 boys aged 2.5 and 4 and I found the promise of "flexibility" seemed to be very one sided and was just a word used because it was the right thing to do. That first job back made me redundant and so I was determined to make sure my new employers understood that I did need flexibility and in return they got my complete loyalty. I'm happy to say that 9 years later we are still enjoying what each other brings to the table 
even though I went on to have a 3rd child so they lost me for a year....plus the 2 months it took me to settle my daughter in childcare!!
I thought I would mention that this lovely company (based in Richmond/Kingston area) will be advertising a marketing job which would be ideal for returning mums. If anyone has marketing experience and fancies working down here rather than commuting into London, this could be ideal. I've got more details if anyone wants them.
Good luck and let me know if you have any experiences similar to mine.