I can totally recommend (and frequently do) GMX:
https://www.gmx.co.uk/
It's exceptionally easy to use via the web interface but if, say, you're using it on an Android phone, you can download the dedicated app for it.
Although not as well-known in the UK as Gmail (et al) GMX is part of United Internet Group, which is one of the world's biggest providers of internet services (so it's got a good pedigree and isn't likely to go bust).
It's got loads of useful features, such as excellent spam and virus filter and the ability to create email aliases. If you choose to use them, there are also excellent organiser and web storage facilities to (all free of charge).