Hugh
i currently have two different rigs and both fit into the back of a car or van, a colleague has a different rig which fits in his car, all work perfectly well. I spent quite some time looking at the different rigs on the market when I bought mine over 2 years ago and eventually came down on the side of one made by Anderson Fire & Rescue Equipment, not to far from you in Dumfries mainly because of the build quality.
The Anderson kit has a good set of control gear, waste bin, monitor, flammable liquid container and a decent size tray, all for just over £2000.
My other kit comes from a company in Loughborough, can't remember the name but I picked up a £1100 set on Ebay for just over £300 brand new.
All are easy to use and can be set up, tested and ready to go in 10 minutes. I know over £2000 seems a lot but my plan is for it to last 10 years hopefully with any testing and replacements and it is always on hand.
I did look at hiring on behalf of one company and it was about £300 for a week.