I've asked friends exactly the same and here was their advice to me:
Ensure freezer is full of meals for both the adults and the DC. Do a 'big' shop so you've got a months worth of toilet roll/dishwasher tabs/washing powder etc etc in.
Make sure you're really on top of all the household stuff, so have a big clear out, deep clean house i.e get windows cleaned, clean oven, file/deal with all paperwork etc so that house is easier to maintain.
Do the same with your car, clean inside and out, check tyre pressure, fill up with washer fluid/oil/petrol.
Make life as simple as possible so arrange for all bills to be paid by direct debit.
Put a list of morning and evening routine up on fridge (or wherever) so that you/DP can do a mental check-off before heading out to work. This should include things that must be in DCs nursery bag.
Get your and DCs clothes out the night before so you know what you're both wearing.
Make sure you know where your work mobile/laptop/car park and building pass are, get some cash out for coffee and lunch. Ask someone in your team to get a password reset for laptop/PC (you won't remember it after a year!) and let you know what your new desk telephone number is. Take a tin of biscuits in for team!!
Keep the first weekend after you've returned to work activity free so that you can just chill - don't underestimate how knackered you'll be!