Jan-TBH I think that's probably a little steep if it's an independent garage-I would estimate you're looking at around 3-4 hours labour (have they included alignment in that price?) to do the job on a F/TF. The biggest obstacle will be snapped bolts, but they should be reasonably easy to deal with on a workshop lift.
To give you an idea-we charge 3.1 hours labour to change a Citroen Dispatch anti roll bar, which is ball joints disconnected, steering rack disconnected etc, subframe dropped and ARB swapped, plus alignment afterwards. The amount of stuff to take off is quite similar to an F/TF.
I would expect an independent garage to be charging around £50 per hour in Wales (I.e. not somewhere "big city" and built up).