Hi, lovely news, how exciting!
You will need at least one cat carrier depending on size. Also a litter tray big enough for 2 cats. I prefer the hooded ones. Cat litter (check what they are using just now and use the same initially, you can them phase onto your type of choice. I find low dust clumping (John Martin from Asda) is perfect for my house cat and very good value), food, again, whatever they are eating just now, should be a good quality kitten food with at least some wet at this age. Litter scoop, a cat scratch post, possibly some cat nip spray for it to encourage use.
A feliway spray would be good if you can afford it, spray it into the carrier 15 mins before you get them and also anywhere in the house they are likely to be at first. A good sized water bowl, and food bowls (you can use your old tea plates for their food bowls if you have them). Decide where they will sleep (do you want radiator beds, igloo beds or leave them to choose sofa's/human beds?) and perhaps get a few cheap fleeces for them to have. Ikea do huge ones that can be cut down, are very cheap and wash well, dry quickly etc.
You should think about a room to have them in to settle them at first. They may be a bit overwhelmed and would probably prefer somewhere with safe, comfy little hiding places to explore from. Register them with a vet asap and get them checked over. They should have been flew treated and wormed recently and have had all their jabs. They will also need to be neutered if not already.
Some very knowledgeable posters will soon be along with much better advice soon I'm sure. Oh, and don't forget to post pictures!