I got mine from John Lewis and did a click and collect, which meant that no worries about security, but I still got their extra warranty. they let you collect at Waitrose and other places now instead of the stores.
It still means I can go to the Apple store if needed to ask about anythign (or at least call them these days I guess, not go in!).
I got a Pro, the 2018 version as the new ones had just come out, and I got the smaller size and smaller memory, as that was fine for me without streaming etc. - I just use it for work.
I particularly liked the pencil (second gen) for the sort of work I do. the second gen pencil just magnetically clips to the side of the Ipad pro (not sure about the others) so it charges whenever it's attached without any special attachment or plugging in, and there is no pairing needed or anything, it's just automatically ready to go. It doesn't come with a spare tip like the first gen though, which is a bit sneaky of them. (I'ts not that expensive, £19 for 4 new tips, but more the principle of it!). I've not used a new tip yet and I've had it nine months with daily use. I think I could probably use a new tip though, but that's more because I've dropped it several times!
I'm not sure I would use it for a lot of office apps though. Mine is mostly for meetings, and using the whiteboard in that, and also various other apps.
I have an Apple folio case with keyboard, and a 360 degree swivel stand that lets me set it up high on the table and turn it in all directions, which is helpful if I want to use the reverse camera to show someone something on the table for example, aand then switch back to the normal camera for the meeting. However, unlike my old keyboard case, this keyboard only works when the iPad is in it. So if it is on the stand, I can't use the keyboard case, and have to get out the keyboard from my old case (which doesn't fit the new iPad as a case, but works fine as a keyboard). So beware of little things like that.
I would also like to use the Ipad for reading music, so kind of wish I'd got the larger size, but it was too expensive!
John Lewis do 'returned' ones at cheaper prices at times. They're not necessarily refurbished, just returned as unwanted, and they can show you what the condition is like - I got a phone from there where it was clearly unused as the plugs etc hadn't even been unwrapped. It was still about £200 cheaper. However that was only available in store, and I don't know if there is a way to find similar on their website.
You should be able to watch prime video etc on it, and if you are just streaming, then I don't think you will use up the memory, though obviously you will if you are buying.