If you do it, I recommend taking the CMD Arete route it was amazing. I'm no athlete but you'll need a basic level of fitness and decent walking boots. Some easy scrambling, we did it in 7hrs iirc.
I did the Annapurna circuit with an organised tour (Intrepid). The highest part of the circuit is the Thorong La pass at over 17,000 feet but it’s all walking (no mountaineering at all). Unlike the UK you will have altitude to contend with which affects people to varying degrees. Acclimatisation is crucial. It’s not for the feint hearted but it’s not tremendously difficult either (just hard work and uncomfortable).
As easy. As mentioned, Im definitely no climber. The great thing about doing the Annapurna circuit is that as its a circuit you dont need to go along the same way, so your view is different for the whole of the trek. As mentioned, there are loads of little villages where you can rest, get food or stay the night so it means that whilst its multiple days, you dont need to carry loads of gear, and you can pace it however much you are comfortable with. If you wanna do 8 hours of solid walking to get to the 3/4th village on the way, you can. If you want to do 2 hours today because your knackered, also no problem. This is the great thing about this route. There is I think... 1 "hard day" if I recall 8 hours or so.... This is basically to go from 1 side of the highest point (5416m) to the next village as there isnt any other villages between, but this is in the middle of the trek so you'll tend to have gotten used to distance by this point. If at any point you were to be uncomfortable with the way (which honestly its easy from a "technical" standpoint), you can simply go back the way you came and stay at the villages you already passed. The whole way is well marked and if I recall doesnt require any pre-booking, simply turn up in the town at the begging and pay a trivial number £ for a permit which has no expiration (again, take as long as you wish).
I only ever did solo rock climbing in my youth in and around Yorkshire so not familiar with the route you did. Would it be as easy as walking up the UK mountains or is it more involved with actual climbing ?
To be honest. I'm not. Even suffer from vertigo a little. The Annapurna Circuit in Nepal is not very technical at all and you can do it in as much or little time as you want (there are little "villages" on the way to stay). It is however multi day to do the circuit.