[Simon]

It will be hard to do anything unless you either have access to the registrar's control panel to renew the domain, OR if the email you were sent has a renewal link in it that lets anyone renew the domain. What I mean is the domain gets renewed but the current owner retains ownership.

Otherwise you'll need the owner of the domain to do something. Probably too near the expiration date to transfer it to you at this point, but he could either renew it, let you renew it, or let someone else renew it for you.

Without knowing the domain name I can't look up anything to see what other options you might have.