Just an update...

Found 2 companies on the web (not one of the big two suppliers) who will sell me just the panels and fixing bolts and am waiting on their quotes. I'm also in a long email conversation with one of the big garage manufacturers who are close to agreeing the same thing, though its not something they normally do. But their price is only £24 inc VAT for a standard panel 2m x 0.6m... that means the whole workshop will be under £800 for the walls (by comparison the other major manufacturer will only supply 'a limited number of spare panels' at £70 + VAT). All in I'm looking at under £3500 fully insulated and ready to use.... ok I have to build it myself but hey, how hard can that be?

I've looked at acquiring an existing garage... even one thats close to me and is big enough to make it worth considering (arbitrarily set as the number of panels I need to add is no more than 1/2 of what's there already) will need a 3.5tonne van to shift it and thats going to cost me £150+ to rent for the day so I'm looking in total at getting on for £750 to a £1000 second hand... might as well buy new and avoid the hassle and effort of carting it over...