my email domain & web page is with an expensive provider- if I move to a cheaper isp do I lose access to these or is there some other way of keeping my web page which I am told I own.

You would lose the domain IF it's part of your ISP's set of domains (or perhaps a subdomain). If, however, they registered your own private domain name for you as a part of their service, you could go to another domain registrar like GoDaddy and transfer an existing domain to the new service. From that point onward, your domain would be independent of whatever ISP you are using.

You would normally lose them, however AOL are letting ex-customers continue with free access to email, but not web pages.

Surely you can ftp to your webpage and download all your assets and move them to another website. Similarly, as long as you own your own domain, e.g. myname.com, the new ISP can redirect all future mail addressed to you@myname.com to you. It's only those that are like you@bt.com, etc., that cause problems.