Hi James
We have electroplaters here who can successfully chrome plate plastic, so surely in the UK you'd be better off. A lot of them even 'bronze' baby booties by coating them with an electroconductive compound, so I had some Beta seat bits and a Fulvia 5 spd bonnet air intake done beautifully.
Our son has also used Dupli-Color
www.duplicolor.com Chrome aerosol spray to good effect on Montecarlo taillight surrounds.
Kindest regards