I would recommend Oxlic acid treatment for the rust, if it is available in the UK. My 84 Colnago also was rusty, but not to the extent your pictures indicate. This is a poor picture of before but you might get the idea:
[IMG]
P7070952 by
superissimo_83, on Flickr[/IMG]
After:
[IMG]
P9161264 by
superissimo_83, on Flickr[/IMG]