Jeesh I wrote a reply and somehow it didn't post.
I'll write it again. Thanks everyone for the great feedback. That's exactly what I was looking for. I'll take it apart then and sell it on Ebay and maybe post on a couple of UK bike forums first to see if anyone's interested. I agree about Ebay, not somewhere I'd use given their track record but maybe they have a monopoly. Thanks for the price alert too. If I don't get much for it I won't be too disappointed, it lasted me 20 years without issue.
While it's in pieces I'll have no transport so I guess I'll go out and buy myself a new bicycle for the next 20 years then.
Thanks again, really helpful advice.