It has a lot of uses as it helps collect water/condensation as well as fire proofing. Could have been used for either/or in your case.
Depending on the age of the property SOMETIMES it contained asbestos so just bare that in mind.
I can't help but think things have gone a little off topic here....
REGARDING THE QUOTE AND ORIGINAL TEXT:
The quote of £3k + VAT you (Yellowduck) have been given does appear excessive given the fact that the machinery is already supplied and that the the garage is presumed as non asbestos...