Well, I bought a skid plate as suggested by Willoughby, above. It was about £140 inc postage. It is strong sheet and will certainly support any bash. It fit like a treat. I cut a slot, a sort of trapeezium shape for oil plug access (the oil comes out sideways, so needs a slot). I'd thought I would need to put a plate over this access hole, but no need at all as sheet is so strong and there is some clearance. However, I will confess I took my measurements looking up, then turned around onto my knees and then marked the memorized measurements onto the plate which I had laid beneath the engine and cut it out and then began to bolt it on and noticed that the slot was on the wrong side. Yes, a mistake, but to be fair on myself it could easily happen to anyone, which is why I mention it here. So I took it off again and cut another slot, began bolting it on and noticed it wasn't perfectly under the plug, but it will do, but I mention it so that anyone fitting a plate this way with a cut out oil plug access hole will take great care to get it right; double and triple check.
Another thing worth mentioning is that I tried a new system to raise the front end. I don't really like the metal ramps as a bit too flimsy and unstable for me, so this time I used a stack of garden paving slabs laid stepped, and a brick so i don't over shoot. I parked the van on an incline facing down hill, put the slabs infront of the front tyres and then simply drove up them. It was perfect, easy and very sound and stable. So when the front end was thus raised the van was thus level, and because of the incline there was more room heightwise for me to work under the engine. This way is a very good system.