Renault Extra 1.9 Diesel Van - Help needed please

Hi

I am the (lucky?) owner of a Renault Extra 1.9 Diesel Van - Seems that no one on the planet owns one of these except me at the moment, seeing as I cannot find one single scrap of information or help on this vehicle.

Anyway, I am looking for assistance from other owners regarding a particularly problem with the Van.

I have an amount of Oil present in the coolant - This MAY be down to a leaking head gasket, although the Van runs fine.
I would like to perform a coolant flush, but need advice on this, as apparently there is a certain order you must do things (or perhaps a special tool needed for this). Alsol, I am unable to find a drain plug, and the bottom radiator hose is unreachable.

If anyone can help, please email me - My address is [email protected]

Thank you in anticipation
Chris