Sounds as if the heater matrix has failed and is leaking. I fear this will be costly if the dashboard etc has to be removed to replace it. You could try Radweld/Bars leaks or similar stuff in the hope it stops the leak.

I doubt that he is.

Seen mechanic today,looks like he was right but there is a smaller rad inside dash for the heating system and i was told to try a good rad seal first ,will let you know how it goes thanks

The smaller rad inside the dash IS the heater matrix I mentioned above.