Thanks to everyone so far for your help
Glad to say I have signed up with Sky and got everything set-up, using my Airport Extreme as a router. I have turned broadcasting off on the Sky router. Just one issue remains - I can't get my Slingbox working, remotely or otherwise. On the Airport Extreme, it is set up on port forwarding, and I have tried setting up port forwarding on the Sky router with the same details.
It worked prior to switching to 'bridge' mode on the Extreme - any ideas how to get this going? Ta