If you can afford a new radiator that would be by far your best option - or even a secondhand one if you can find a good one.

Radweld may effect a temporary cure in an emergency but it may also clog the heater matrix. If you have to keep topping it up you are loosing antifreeze, that isn't good for the engine either because of the corrosion inhibitors it contains.

There is new one here for £35.00 inc delivery:

http://www.ebay.co.uk/itm/Radiator-VW-Golf-Mk2-1-6-1-8-GTI-16v-430x322mm-NEW-/310298855223?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item483f40c737

I have noted the helpful advice.

After driving I have checked the coolant system when it was hot, the radiator was more or less dry. I only see coolant a day after when everything is cold, I also see some coolant under the bypass valve.

There is a lot of lime scale around the coolant pipe connection to the carb housing, again though it is dry after checking when driving and when cold. Could this be the main source of the coolant leak?

Exchange rad from Serck.

If there are any scrappies in your area, give them a call. I got a great radiator for £20 a few years ago.£30 is fine, but postage bumps it up to £50 which isn't so great.

It' is common for radiators that seldom get hot to corrode and start leaking.