more details and welcome aboard Paul
colour, year, gt ?, coupe, miles, loan needed,apr on the loan, cost of insurance, tyre tread depth, private or garage ,girlfriend or married, working or in IT
it could be the system needs a flush, this would cause these symptoms, i think i have read before about a zed having sludge in the heater core
check coolant level
check the radiator is not obstructed (suprising what can get stuck on there, plastic bags, leaves etc)
A) take £14k now and say goodbye to the car. This isnt really a viable option for me as i would loose 20K straight off and wouldnt get a car anywhere near as desirable as the car.
the car cost 34k ?
if you take option D will it be recorded ? i.e. a cat c or d ? this will devalue the car greatly if so
Buying parts to repair doesn't seem viable to me considering the value of these cars, it will be a cat d and very difficult to shift come selling time
maybe its time to take the pay out and start anew