I stocked up before both babies and it was fantastic.
I second/third a lot of the above suggestions. Also:
Sausage casserole. Google the hairy bikers recipe - I add extra peppers and shredded kale. Lovely with some crusty bread
Leek and bacon creamy pasta bake. Delia recipe - very rich but just the job for hungry days.
Chicken in white wine, leek and mushroom sauce. Add a little cream or creme fraiche before serving with rice.
Beef stroganoff - slow cooked stew type. Again the Delia recipe is great and you can stir in sour cream before serving.
Beef goulash or Beef Bourginoun (or any type of beef casserole)
Scones, Nigellas Apple and Spelt Muffins, Choc chip cookies (freeze the scoops of dough and bake from frozen)
Not something you cook in advance as such but I stocked the freezer with frozen fish, oven chips, peas, sweet corn etc. Buy lots of biscuits for visitors (you may or may not eat these if you go overdue!) and plenty of essentials like toilet roll.