Most ISPs can provide them, with various features from POP/IMAP to use with a standard email client, to full ms exchange. If you're happy with a gmail address then that's is fine, but if you want something more personal and not dependant on Google.....
I have a .me.uk domain name from Fasthosts with standard POP/IMAP and webmail access at £2.40pre mail address per month (£1 per month for the first year), plus the annual domain name fee. I can transfer that domain name to any other provider if I want to, and then set up the same email with the new provider, so I am not tied to any individual company.
https://www.fasthosts.co.uk/email-hosting
I hate fasthosts with a vengeance... just look at my signature.
They ripped me off years ago.
You are correct that that you can migrate to another supplier (read: domain registrar), but you often have to pay the domain registrar a fee for the IPS tag to transfer to a different domain registrar. Fasthosts currently say that they they don't charge. Based on my previous experience of using them, I am skeptical.
Other firms to avoid are Godaddy and BlueSquare.
.UK sites fall under the remit of NOMINET, domains such as .COM, .NET, .ORG are ICANN.
NOMINET allow domain names that are being used for personal use to be excluded from the WHOIS database (at no charge). Registrars such as Godaddy will charge you a fee for that privacy, pretty much charging an additional fee for a free service.
My go to domain registrar at the moment is NameCheap, they are significantly cheaper and don't hit you with hidden charges.
For the last 20 years I have had a reseller hosting account with
Total Choice Hosting. I pay $20 per month but I can point as many domain names at my webspace as I want. If a customer wants 5 email addresses to go with their domain name, they don't need to pay 5 times £2.40. That said, if I am hosting their service as a freebie, I will only give them a small amount of mail box space. That was less of an issue in the days of POP but it is more of a problem with IMAP.
Total Choice Hosting, at the lowest tier currently charge $3.47 per month, BUT you also get website with that and the possibility of more than one @ email address. Additionally, in my experience, their customer service is excellent.
The cheapest option however would be to use a free hotmail/Outlook or Gmail account and point the MX records for your domain at your hotmail/Outlook or Gmail account. I don't see either Google or MS going bust at any point soon. Once set up, you will only be paying for the domain name.