Offer them no more than a grand. If the car has been stood in a garage it might not be too bad condition. Watch out for seized rear brakes (if so take rear wheels off and tap drums with a lump hammer to release brake shoes). Handbrake cable is a two part type and connections tend to seize up. Get underneath and wipe crud off all the cable with a rag soaked in paraffin. Check front brake callipers are ok. Might need a good clean thats all.
Starter motor and alternator should be ok. Charge battery or get a new one (forty quid). Check wiper motor is working and screen wash. Basically have a play with everything on the car and see if it works or not. Defo not worth two grand.