Hi
@joanne75 ,
I'm not a pumper. & I can appreciate you are essentially a "pedestrian."
I've driven many times using the tunnel crossing. & it's nothing like using an airport.
All in all fast, relaxed, & easy..
Security can pull a car over for spot checks from time to time. But they tend to just keep you waiting for a short while & "swab" the car door handles.. Presumably for explosive residue? (Lol, in my experience.)
Never been through a metal detector or X ray'd my posessions either.. Regarding these security checks..
You just need your booking & passport.
The last time I went in September was with a dog. The only scanning was with the chip in the hound's neck to verify his pasport regarding his vaccination was upto date on the way back.

He didn't even have to get out the van? They handed me the scanner to do the job so the animal wasn't upset by a uniformed stranger..
I actually find it all quite civilised.
I hope someone with the experience of traveling via the actual Eurostar comes along soon..