I considered all the options but n the end I decided that i should stop trying to save a few £s and ordered a Asus rt-ac86u.
Mesh systems or wifi boosters just seemed like I was trying to patch up an issue with the superhub when really it is the router that is not fit for purpose. I'm hoping going a far superior router will just provide a good 5 Ghz signal across my house and garden (kids can then video call grandparents etc when playing outside without signal disappearing). I dont have a big house or particularly demanding one.
I actually messed with my superhub last night and separated the 2.4 ghz and 5 ghz channels and moved most devices to 2.4 Ghz. Tbh connection is now more stable throughout house but still not great signal strength and low speeds. But then this morning i got immediately annoyed as then why then am I paying for 200mb speeds but getting maybe 20mb in some rooms or having to mess with continually changing between 2.4ghz and 5ghz.
I'll post an update on everything when I get the new router up and running.