Firstly, get all those little jobs you've been meaning to do out the way before pup comes home. Once he is here you will not have time for any of them 
Stock up on shoes or slippers you can easily pop on to go outside (crocs!), a warm dressing gown and a torch. You are going to need them for night time toilet trips.
Get plenty of kitchen roll in (Regina Blitz!). More than you ever thought you would need. Plus a good enzyme carpet cleaner (Simple!) for cleaning up messes. If you have a carpet cleaner tucked away, get it out ready. If you know someone you could borrow one off for a few months, do so.
Get a few bits of vet bed for puppy to sleep on. They wash very easily and having some spares mean you can easily switch them in the night if he has an accident.
A little collar, lead and harness so he can start to get used to them in the house before going for walks. I loved Perfect Fit harnesses when mine was a puppy because:
a) they can be put on without pushing anything over the dog's head, which young puppies may not like
b) you can replace individual bits as the dog grows, just slowly making the harness bigger and bigger
Book the vet's appointment for a check up the day after he comes home - to make sure he is as healthy as you hope and to get vaccines started.
Find out what food he's being weaned onto and how much the breeder will send him home with - then get a bit more in. Look at allaboutdogfood.co.uk for food reviews to help decide what food you want to move him onto, or if to keep him on what the breeder uses.
Get a copy of The Happy Puppy Handbook by Pippa Mattinson or the Perfect Puppy by Gwen Bailey. Both very good.
Sleep all you can now. It's going to be in short supply soon!!
Post pictures. LOTs of pictures