So I decided on the K3 (75% as I figured maybe I'd like F keys at little cost to size - nothing horizontal anyway), but in my haste/excitement I ordered the US layout. I've emailed asking if they can cancel. It's not the end of the world if they don't, but given they seem to take 3 days before packing, hopefully they can cancel and I'll order the Uk version.
Can often be acquired cheap. I also have very expensive Logitech keyboards, which I now have on a bookshelf gathering dust. The lighting on the logitech G915 and G715 are definitely better, and when I feel the need to go back to low profile keys I will switch back.