I tried to stock up on a lot of 'quick' stuff, as breastfeeding made me super hungry, but I stocked up on things like:
Pasta (the bachelors ones and normal pasta for me to add sauce too)
Rice to use as sides
Noodles
Tinned foods (including veg etc, just for if you don't get chance to do a shop!)
Cereals - porridge pots, cereal bars etc
Crumpets, bagels, croissants
I use my slow cooker a lot, so I had stuff in to use in that! I had steak, chicken and stuff in the freezer to do casseroles, I also had tinned potatoes and corned beef to do corned beef hash, super easy and I could go back for seconds and it still be warm 🙈 also a few weeks after my first baby was born, I used this hack, and I still use it! I bought zip lock bags, and prepared loads of different stuff, so I had zip lock bags with 'chicken casserole' written on, and in that was enough chicken, veg, etc, for a few portions, then I could just get it out the freezer to defrost, and throw it in the slow cooker, made life so much easier!
I also tried to make sure the cupboards were stocked up with stuff that had really long use by dates, just so if we ran out of anything fresh etc, I had enough to go at!
I also stocked up on UHT milk, so that if we ran out and I wanted a brew, I didn't have to go the shop/get somebody to go the shop and wait, I had my emergency brew milk as a back up (still something I do!)