Thanks for the replies, I think I'll buy a split link and connect the old chain and ride it, slowly, to a garage (the old chains pretty twisted so it may go again!).

I'll then get them to fit a new chain and sprockets.

Although I have the cutting and linking tool I don't have a paddock stand so can't see how I'm going to get the rear wheel off.

Oh well, I guess I know what I'm doing this weekend!