wheels, wheels wheels, so much choice...

With that average speed I'd say that any aero benefits will be minimal, unless you ride somewhere very hilly and that's dropping your average. That's not to say that you shouldn't go carbon with a minimal aero section - 35/40mm would be the sweet spot probably. Are your bikes rim or disc brake? If disc then full carbon wheels would be a nice upgrade but I wouldn't be spending more than £700/£800 on them. Unless you're racing there are pretty minimal gains to be had from any wheelset, let alone mid-high range upgrades. These might be a good starting point, well reviewed here - https://road.cc/content/review/247978-just-riding-along-gecko-carbon-whe...

Off topic - but why are all the Latest Topic Forums about buying cocaine / heroin / etc. with Bitcoin?  

There's a massive difference between the wheels you probaby got on your bike when you bought it and a set of GBP600 wheels - wheels are where bike shops save money - but then the step up to a GBP 2000 set of wheels from GBP600 is a massive step up again: especially if you land a set of Enves or top end Bontrager... 

There's a reason why pros don't ride Halfords' wheels.  But the returns are diminishing, of course.  Moreso for us mortals.  

Unfortunately it is the law of diminishing returns. A good £600 wheelset will feel faster and more nimble than an entry level £80 set...but spend 2 or 3 times that and you will find a much bigger difference on a day where you have good legs. A large amount of the cash spent on expensive wheels will go directly to the marketing dept who come up with "Oojemeflip" bearings, and natty phrases on why they might turn you into a world beater.

https://intheknowcycling.com/ - go to Read the Reviews