Engine repair - Main/Top Gasket

Hello Bedforders,

I have a lovely 1981 Vauxhall Bedford Hymermobil Spritz with a 2.1L (i think?) diesel engine.

Unfortunately, after a 500-mile drive, the head gasket seems to have failed. I had just pulled into a gas station and let the engine idle for about 30 seconds when it began making a louder knocking sound. White smoke started coming from the exhaust, and about 20 seconds later, I heard a puffing noise from the engine. It then struggled to maintain idle and nearly stalled.

I’ve been unable to find a Haynes manual, parts list, or any engine diagrams. Do any of you brilliant and knowledgeable folks know if it’s possible to repair this with just my common sense and basic tools?

Thanks in advance!