Hi,
sorry dont know of any one particular reliable maps or internet sites that shows the centres/sites that is up to date,
but if you just google the Name/place followed by 4x4 you will find threads/websites/map/directions etc,
there arnt that many commercial places in Scotland.
My list below doesnt have the ones near Loch Lomond, Inverness or Aberdeen.
Here are some, ?20 day to over ?100 type thing.
Much depends on if going on a group booking,
Club outing or private tuition.
('Nortrak' doesnt exist anymore.)
Lamancha, (nearish to Penicuik)
Drumclog, (near Strathaven)
Glantarkie,
Newton Hill Country Sports, (both Fife)
www.tay4x4club.gdnetwork.co.uk Crieff Hydro,
Hilton Dunkeld.
Auchcterhouse Country Sports.
have fun.
george