It is not likely you will find parts for free. However for older bikes you can try shopping cycle breakers for better prices than the local shop.
Here are some UK breakers. Most will ship what you need, if you can't easily get to their place of business.
http://search.yahoo.com/search;_ylt=A0oGkmGBVKNKS08BKl9XNyoA?p=%22bike+breakers%22+uk&y=Search&fr=fptb-sbc-153&fr2=sb-top&rd=pref&sao=1