Yeah, that BBC site is great isn't it. 'The Risk Business' will be a babyhum release at some point. A friend managed to find a great quality beta-max tape of it.
As for the other things on your list, I think it's unlikely that we will find the 1977 tonight or the 1978 Arena unless the BBC re-broadcast them (wouldn't that be great though!). I have contacted to the BBC in the last few months to ask if they had any plans to celebrate Star Wars' 30th Anniversairy. The replies saying "we have no current plans". I kicked myself for not getting on this quicker, perhaps we could have got something done.