How much would l expect to get for it if sold privately or part ex thru a dealer ???

try going to auto trader site, they give prices for used cars.

Selling privately might get you somewhere between £1,200 and £1,500, depending on model, condition and your sales skill.
Part-ex would depend largely on what you were buying, and what sort of profit margin the dealer had on the new car, but £1,500 would be a good start.