If any of the asbestos is damaged or is showing signs of deteriorating you can try your house insurance - some play ball and some don't.
If it is dismantled, bagged and labelled then you can book a slot at Bidston tip where you can dump it for free.
Get loads of quotes, many firms try-it-on because of the "A" word.
That's is generally true if you know all the asbestos is cement bonded..if its the corrugated roof sheets than that's almost certainly ok. Its the side sheets I would be more cautious over especially if they are flat and not corrugated. Mersey waste will probably give you the ok on the side sheets without the need to have it officially identified.
As the homeowner you can tip for free but a contractor cant take it to the normal tip and that puts price up (if they are disposing of it legally). Technically if you just pay for someone to take it off you cannot then take it the tip yourself-- crazy rules. You just gotta not look too guilty when they ask did you take it down yourself. Its ok for the odd sheet doing it yourself but bit of a job with a whole garage. Its not the real dodgy stuff when they turn up with white suits respirators and clean rooms to shower. You just try and avoid snapping or drilling the sheets.. not that the world will end if you do. Normal dust masks I think as well.
Guess prices around £800. Anything over that especially in thousands and they are playing on the "A" fears as DD said