As well as setting up a redirect for both search engines and users alike to follow, those that already have the "wrong" URL that is, you also need to hard code the link on your site to point to the "correct" URL. This is vital.
For the .htaccess code, see the Apache forum here. The "index file redirect" question is asked and answered on a fairly regular basis.
I didn't realize I could find answers in the Apache forum, certainly my brain is getting hard coded into a jelly fish.
Thanks for the advice, will keep trying, even though I don't seem to get it to redirect for some reason. The .htaccess provided by this CMS is huge, so it could be something overriding the new RewriteRule I've set. No idea...