New firmware has been installed on the router, it's pretty simple and straight forward.
Chillispot (for the captive portal) can either linked to an existing provider (who will serve the ads for you and take a commission) or find captive portal php software and run on a cpanel web host. I'm going down the latter route, have amended the old code to work, evidently I need an IP address rather than just a URL, so have spoken to my host to organise.
Aside for those who are interested, I've a site, content and logo. So once I've nailed the captive router, all should be good to go.