I'm in the US too, but I think the standard in the UK is 25 year mortgages, whether fixed or adjustable I don't know.
They also seem to have a more risky house buying process in the UK in which contracts aren't exchanged until a considerable amount of time and effort is expended and the seller can sell to someone else. For example, a home inspection is performed there before contracts are signed, whereas here they are often done post contract signing with a kick out clause for the buyer if the news is bad.
Interestingly, it seems like there is much handwringing about offering a lower amount post inspection if there are problems. Buyers seem to be afraid of insulting the seller.
Whereas here, a bad inspection usually involves further negotiations and the seller can refuse outright if he doesn't want to negotiate the price.
We bought our first house with an adjustable rate so we could qualify. There were limits with how much it could increase. We sold within five years and all our mortgages since have been fixed.