There's not really a huge amount of stuff you need for a new puppy. Food and water bowls, a basic collar and/or harness and lead plus legally compliant tag, appropriate grooming equipment (depends on breed/coat type exactly what you would need but you'll definitely need nail clippers), some puppy appropriate toys, a cheap basic bed (in case the destroy it, I like to use VetBed as it's comfy and easily washed but fairly tough), a crate if you want to use one, some proper cleaner (Simple Solution stuff is good) for the inevitable accidents and obviously plenty of poo bags.
Don't bother with puppy pads, they aren't particularly helpful and can actually complicate toilet training in the long run.
Is the puppy coming from a breeder? If so they should give you a supply of the food they've been weaned onto which it's wise to keep the puppy on for a while before switching if you want to.
The puppy should already be microchipped when you get them, it's a legal requirement now. Some breeders will get their first jabs but it's wise to check if your chosen vets use the same brand of vaccines. Different brands can have differing schedules which could mean restarting the whole course. You can always ask the breeder to hold off or see if your vet can get a different brand in if necessary.
Start looking into insurance before you get the puppy. Breeders should send pups home with a period (usually four or five weeks) of free insurance but you want to have ongoing arranged before that runs out.
Also start looking into puppy classes before you get the pup. The FB group Dog Training Advice and Support (run by highly respected professionals who promote the use of science based, force free training methods) has a list of puppy classes by area in the 'Files' section. You can also post in there and get recommendations. Go along and watch a class or two before committing to them, decent trainers should be more than happy for you to do this.
There's loads of links to really useful information on this thread, it's well worth having a look through and