If you really really want to get ‘into the weeds’ on finding out what you can get, start here
https://www.thinkbroadband.com/broadband/availability
That will show you wish technical options you have in your area - Virgin Cable, Openreach FTTC/FTTP or TalkTalk/Sky LLU (as well as ‘standard’ broadband).
Virgin Cable and Openreach FTTP should be the most reliable (with least amount of drop outs etc) as those services give you a nice fibre optic cable from your house all the way to the telephone exchange. It does also give you the most ‘flexibility’ in terms of once it’s installed (you will need to have an engineer come around and install it if your current Sky package isn’t already FTTP) you can pretty much pick a speed between about 40Mb all the way up to 1Gb that’s right for you. I’d suggest going for around a 100Mb package to start with. If you decide you need more, most providers are happy to upgrade (although that might restart your contract) although not happy to downgrade.
FTTC isn’t quite as good - you’ll have a fibre connection from your street (ish) back to the telephone exchange, but from the box on your street (ish) you’ll still be using the old copper wire from (probably) the 1970s. (btw - I’m saying 'street (ish) because those boxes are not necessarily on your street - especially in rural areas).
I’d ignore LLU - that was going to be the ‘big thing’ to break BT’s dominance in broadband provision in the 2000’s, but hasn’t really made much impact. Technically, it means you still use a BT line from your house to the telephone exchange, but it hits the LLU provider equipment in the telephone exchange itself, rather than then go across Openreach equipment at that point. It means if there’s a fault, Sky or TalkTalk could have their own engineers fix it, but I think both of those just use Openreach for everything now anyway and you wouldn’t see any difference.
Other things to consider though - what other ‘technical’ services do you have from who? Most (all?) Mobile phone companies now offer broadband as well, often discounted for their mobile phone customers so you might want to check out their packages. If you’re cancelling Sky TV, are you getting any other TV package to replace it? Now TV for example (which, ok - also from Sky) but they also do broadband. (Now Broadband, powered by Sky Fibre is £25 a month for a 100mb connection).
Also, as it’s been mentioned, to get good coverage around the home, you probably need to put the router you get with the connection away once you’ve been setup and go and buy a specialist one.