You won't notice any difference between P90 or humbucker at this stage of your 'career'. Buy the one that feels nicest to hold.
Even though you can't play, you can still do a couple of simple checks:
* Run your fingers along the sides of the neck, to check for any sharp fret ends
* Play a single note at each fret, on all 6 strings. You want the notes to ring clear, and you don't want any string buzz.
A clip-on tuner, like a Snark (
https://www.andertons.co.uk/silver-s...ner-red-silver) , is a great accessory.