Not sure my experience will help, but here goes anyway. Rufusmcdufus, how long has she been at nursery? I'm working full time (2 days at home) so my 7-month-old DD is at nursery four days a week. Although she seems happy there, she's been on hunger strike and has gone from sleeping through to waking for night feeds (or just waking and being fretful) and starting her day at five-ish to get the extra feeds. Although completely knackered, I'm quite pleased as she was losing weight.
However, there is light at the end of the tunnel finally. On Friday, she took milk at nursery (god bless you doidy cup)and ate her solids. We had much better sleep since and over the weekend. So, perhaps things will get better for you and it's just taking her a while to settle in nursery?
Also, we find DH is much better at settling her back to sleep than I am - since we're both working full time, I suppose it's easier for us to share the non-sleeping!
In the meantime, carry on mixing as much milk into her food as you can.
Ratfly - hope your return to work goes ok. You may find DS settles in really quickly, especially if he is used to taking a bottle.