Whether it's going to be bedwetting or worse, you should look up some barrier creams and try them to see, how they work for you. Like, some may be too oily, others, on the contrary, may dry up too quickly. And sometimes, although it's extremely rare, some may give allergy. But again, that's super rare. Applying a small amount to a sensitive part of your skin (inner wrist, for example) should be enough to check this out.
Also, get a plastic or rubber sheet/ mattress cover, because sometimes diapers tend to leak.
Apart from that... If you move a lot in your sleep, I'd recommend an onesie or a diaper cover. If you condition is going to be worse, than simple bedwetting, either of the two is a must have. Which one is up to your preferences.
There is also a common mistake a lot of DLs make, when getting a legitimate reason for wearing diapers. They get themselves the thickest diaper possible. Don't do this. Start with some reliable medical brand, that has thinner ones. I'd suggest Hartmann MoliCare. If they leak, move up to thicker variants. Until the leaks stop. That way you'll be able to save a considerable amount of money.
Now, if your problem goes past bedwetting, get a bag, where you can put spare diapers and other supplies. It doesn't have to be a bag ONLY for diapers, but can be a slightly bigger bag, than you usually wear, that has a "secret" pocket.
Oh, and you should probably get a diaper pail in any case. Throwing diapers away one at a time, when you are at home may be tedious and they usually start smelling after some time, you know...
Apart from that... I think that's about it. I can't think of any really necessary things to have in either situation.