Research ground pumps carefully. I used to work for a company which sold them. You need a lot of land to feed a standard house. Over a few years they actually cool the land around the pipes and so efficiency drops.
Small windows, no draughts equals no air! Be prepared for everyone catching the same thing if one person brings in any form of cold etc. Our local sixth form college installed massive insulation and very clever air circulation technology in a new music block. A year later they pulled it all out and fitted opening windows as the whole department was continually off with any infection going.
Modern heat saving enthusiasm forgets that humans are kitted out to get cold and survive in draughty buildings very well if they wear socks and jumpers....... What Morgan owner hasn't experienced the joy of not being in a hermetically sealed saloon? ( Admittedly not so great when following a diesel that's over five years old!)
I have never seen an ASHP system in real life though watched a few vids, and there seems to be quite a lot more to it, and takes up a lot more space than the various systems I have self installed in my house over the years. I suspect my combi gas boiler fed UFH piped water system with zones stats and valved manifold is simpler and takes up less space than the hot water storage and control systems related to ASHP, but perhaps not.. ?
If interested in possible issues related to AHP you could beam up Skilled Builder as he has done quite a few vids on the subject, though they are padded out to some degree.
In a new build to modern standards an ASHP might make sense. Insulation, installation during build make it pretty straight forward for optimum design. It is designed to run at lower temperature so a steady state is the aim with hot water tank for more immediate use ( shower/bath etc). Another factor to look at is lifespan of components. Retro-fit to older properties means probable insulation upgrade plus a more involved fit of inside heating units. Under floor is often used so more disruption. Storage system alternative? Don’t know. Payback period? As with solar/batteries etc will your outlay be returned in a sensible time? Gov grants? Are they factored in to quotes from suppliers? A cynical thought there! Running costs? How true to life are the figures quoted? Lastly, are you looking to buy in to climate effect scenario? I think of it as similarto EV ownership. Not for me at the moment due to the overall cost, payback, practicality.