We seem to be in classic OcUK mission creep mode again here.
As I understand it, all you actually want is a reliable router with decent Wi-fi that will not need rebooting more than once a year.
A BT Smart Hub will need rebooting once a month, tops. That’ll cost you £30 on eBay.
A Mikrotik hAP AC will need rebooting annually unless you upgrade the firmware. That’s about £130 in the UK.
Right now you’re looking at £105 for a USG, £115 for a US-8-60W, £75-125 for an Access Point and £70 for a UCK Cloud Key. That’s £365-£405 and you’ll need to mount the access point centrally on the ceiling on the top floor of the building to get the best out of it. Great if you’re committed. If you put the access point on a desk or bookcase, chances are it will give very poor performance compared to a BT Snart Hub or one of the better ASUS router/Access Point combination units.
If you REALLY want Unifi then great, the originally suggested EdgeRouter will do the same job for less money. The newly launched ER-10X will handle an incoming connection from your existing modem, up to 8 24V PoE devices (Unifi AP-AC-Lite, AP-AC-LR or AP-AC-Mesh will all run on 24V) and that will cost you £200 plus the access point so £275-£290 all in. And you still need to ceiling mount the access point.
As part of what I do I specify and supervise the installation of these sorts of systems and they are massive overkill for a home user. Where the Cloud Key really makes sense is if you want to install a network at your elderly parents house and monitor and operate it remotely. That’s a snap. If you go home every evening and you’re the sort of person who doesn’t want to update your networking components every 8-10 weeks when the new firmwares are released, then it’s just a £70 paperweight.
It’s lovely kit. It’s just a million miles from where you started this journey.