Quick update for everyone who has been following my posts.
I have given up on using the router I have with DD WRT, it is too old and too difficult to find firmware/hotspot systems that support it, even the Hotspotsystem website describes using DD-WRT as a 'headache'. I almost get there but then come against another roadblock over and over again. I thought I had cracked it when I managed to install 'Tomato' firmware but then couldn't upgrade to the version which had a Captive Portal function.
So in short -
Don't go and buy the router that I mentioned (Netgear WNR2000v)!
I have decided to just go with Cloudtrax that I mentioned before, it is a really simple, plug and play system that I have used before for a WiFi network. And there are a number of
supported routers which I have used before that I know work. By using the Cloudtrax system I won't have to worry about get the WiFi hotspot up and running and just concentrate on the lading page and getting it correctly configured.
I have purchased a cloudtrax compatible router on eBay (£20/$26) and will wait until I have everything up and running before I post anything more!