I got 99 problems but my WiFi ain't one

You're going to be spending a lot of money.

The biggest benefit from Ubiquiti is when all your switches, access points, and the router... are all managed by a Cloud Key. Then you get a great network, but can also see it, customise it, debug it.

Start with evaluating what you think you'd need and how you want to get there.

i.e.

• Router to replace the Nighthawk
  
• AP to handle the Wifi for the Nighthawk
  
• Switch if you have local LAN needs... the AP is PoE and so your switch should accommodate this
  
• Somewhere to run the network management software, or just buy a Cloud Key
  
  

That's bare minimum... but it only starts to shine when you add more switches and routers. If the above is all you need, then don't bother with distinct components at all - instead look at the Unifi DreamMachine. It limits a couple of things compared to distinct components, but not enough that you'd notice.

If I were you I'd start off with a Unifi Security Gateway and Unifi AP second hand. You should probably be able to get both for about £120. That's pretty much the same functionality as the dream machine but a fair bit cheaper and you have more flexibility on where you put your wi-fi point.

If you have a machine that's always on then you can run the controller there. I've run mine on Ubuntu, Windows and Raspberry Pi.

I haven't bothered with the switches (I had a toughswitch but gave up on it), they don't add that much for a home system I feel. Just the USG and AP allows you to set up multiple networks, block them from seeing each other, etc. You can just use an injector for the AP power (it will come with it normally).

One thing to be aware of is that different products come under different families and require different controllers which is really annoying. The Edge Router X (which is very similar to the Security Gateway) for instance uses a different controller to the access points and the two don't see each other at all in terms of managing them.