I’m not sure what rootstock my apples are as I’m fairly certain its not the one I ordered (I ordered minerette trees and they definately aren’t those). Variety is easier greensleeves and falstaff, greensleeves established well pretty quickly and is a heavy cropper which keep well. Falstaff is still settling in (this will be its 3rd summer in situ) but produces a few apples each autumn thus far. I say wait til autumn and then taste your way round the orchard (or an apple farm if you can find one) so that you can pick the one you like the flavour of, then discuss with a grower what sort of root stock works for that tree in the position you have.