A-2-A pump in England, how to get started?

I am interested in an a2a pump but the quotes I can see from octopus and British Gas appear to be for a2w. I want to go with a big and respectable company with long warranties and long term support in place. Where should I look for a2a pumps? What am I missing on why these are not popular in the uk? I am originally from Sweden and “everyone” has an a2a pump. Would seem silly to have all this investment go into it and not have the upgrade of air conditioning