my 15m ds loves nursery - the carers are great, he does loads of different activities, gets to run round a huge garden (we have a postage stamp sized one), plays with lots of other kids...
she might not be too keen at first, but it is highly likely she will settle in well, and get to like the novelty of it all. always remember, in the unlikely event it doesn't work out, there are other options (e.g. childminder), so there will be a contingency plan.
the parenting books i have read seem to say that you should say goodbye firmly with a smile and walk out confidently, otherwise the child picks up on the stress. easier said than done, i know, but if it is at all possible try to sound positive and enthusiastic about nursery to your dd.
it is a real wrench when you go back to work and have to leave your precious child with other carers. after a while, you will no doubt build up confidence in the nursery which will make it easier, when you see that your dd is happy and well cared for.
going back to work is a real strain. i found it quite nerve wracking and very tiring at first but this has got much better now.
please give yourself a chance to adjust to it all - it's a big change. working three mornings a week will still give you a lot of time with your dd.
hope everything works out well for you. best of luck!