Great advice @Nickfromwales which I've followed.
Went to Garscube industrial estate in Glasgow as they have three plumbers merchants close to each other.
Young Callum at Plumbworld gave me a small double radiator for free and insisted on carrying it to the car too!
Graham's had nothing but phoned another branch who unfortunately had just sent a 4 year pile to the scrap merchant.
Next up was PlumbCentre who gave me a huge double for 20 quid, nice fella said he'd give it away but company policy requires an audit trail.
Result, and for all the poor experience's buildhubbers are having, remember this, people are generally nice, kind and helpful.
I told folk it was a charity job and like, their chance to do a mini DIY SOS but without the publicity. Was met with a huge smile and you're welcome.
Few guys in the merchant queue commented too, well done son, you don't ask, you don't get and do on.
Nice experience pre Christmas and saved £160 for a couple of hours driving around.