Are they like normal wheel studs that are driven in from the back of the hub? If so, they're easily available (although you'll probably lose a day of your holiday).

I once lost a wheel off a caravan on the M6. Found two (of 4) of the nuts inside the hub cap. Took one off t'other side, re-fiited wheel and drove to the next services with three on each wheel. Had a look there and realised the 'van had ground off the bottom of the shocker on that side and put a large 'flat spot' on the tyre that had fortunately wedged itself in the body. Drove the rest of the way to my N Wales destination, where I got a new tyre. The insurance wanted to write off the 'van, but I found a place that could weld and thread a rod to fit a new shocker. Insurance insisted on new studs and wheel (which they paid for) and because I'd saved them a good few bob with the repair, didn't ask for the excess.

Yes, but the hub is unusual (these days) because it's a brake drum and I'd need to get it off to work out how to dismantle.

I was one a passenger in a Series III Landrover on a (very slow and long) drive from London to Blackpool. At one point, a wheel went 'a bit' wobbly and we stopped to discover only 2 of 5 wheel bolts remaining. We did likewise - borrowed one off each of the other wheels.

Are they like normal wheel studs that are driven in from the back of the hub? If so, they're easily available (although you'll probably lose a day of your holiday)..

It's decades since I had to fiddle with wheel nuts on studs on a hub. Having had little else but Pugs since then, I have got used to putting bolts into the hub and I guess this problem might not occur ? The wheel is a bit trickier to locate, but otherwise I prefer the bolt arrangement.