Thanks for all your info. We get the sports channels,films etc but are missing some of the documentary ones i.e the History channels and can't get the +1 ones (that doesn't sound grammatically correct). Have an AV adaptor for our iPad on order so hopefully that should help with BBC & ITV. Will also have a chat to Digital Dave. It's not that we watch anything in particular but you always tend to want what you can't have!
I'm sure dave will advise you but probably 3.1m dish is the only way to guarantee those channels. Have you thought about using a uk ip (internet address) and connecting to these channels online via sky's website?