A good strategy would be to post photos of the bike in the forum for C and V valuations...you'll get an honest assessment of it's potential sale price. There is a collector market for Raleigh Professionals, Internationals, Competitions, Super Courses...pretty much any bike with 531 tubing.

As far as donating it, you might have community groups near you that could make good use of it (either selling it to raise funds, giving it to a child for an internal race team...you never know).