2000 Vauxhall Corsa engine oil leaking externally from head

We recently bought a corsa 1.4 16 valve cdx petrol automatic 2000 last of the old shape, The problem we have is oil leaking from the head gasket externally & oil getting into the cooling system. At 37208mls the cam belt broke & the car was recovered to a garage this was 18months ago. The garage replaced all the valves / guides /cambelt kit, we bought the car from a family friend so we know the history of the car. Two weeks ago I renewed the head gasket because it was leaking exactly the same way I was very careful to make sure that everything was clean & grease free before reassembly, but the problem is still there. HELP !. Does this type of engine have a history of this. I am a mechanic by trade but have been on commercials for the past 30 years & am not so familiar with some of these car engines. Regards gerry hale