do this, you might get a pleasant surprise;
benefits calculator
make sure all of your details are up to date with everyone and all of your important documents and valuables are in a safe place
see a solicitor if you haven't already to make sure you are treated fairly regarding contact and maintenance (first appointment is usually free)
change the locks if you are staying put
remove any financial association to your ex on your credit report
make a social timetable and try to stick to it, toddler groups, book club, knitting club, church coffee mornings all cost not much and will provide valuable support; you might not always feel like going but do your best to build a network - talk to parents at the park etc - it takes a village :)
if you can at all create an emergency cash fund then do it now, make sure you have your own bank account etc and cancel any joint accounts or credit cards etc.
ask family and friends to come and help out, if they are far away get them to come for a weekend soon, ask them to bring wine and arrange a date and put it in the diary so you have that to look forward to.
it might be fun, if you have been in a crappy relationship then being single can actually be a huge relief, bed to yourself, tv remote all for you, no more having to buy gifts for the in-laws, the list is endless :)