I did think about booking system - but that would be hard
Oh! 
- as all jobs are different and they do not always go plan so a live booking system may be troublesome
So both hard and troublesome?
You intend to send out an email with an expiring M.O.T. date. Most garages (I've dealt with) want the vehicle first thing in the morning (or the day before) until they are finished so that they can plan their day(s) accordingly. Do you only do a repair at set times? I do understand that you may have to order parts, or wait for Bill to come in cos he's late after a night on the sauce, etc.. I don't know of any garage that can ever fully guarantee a drop-off and pick-up time.
There may well be instances where two people are trying to book the exact time and date, but that's where confirmation pages come in and polite notices stating to wait for the confirmation email.
So you mean pictures of the work - rather than pictures of the workshop? Due to security, I wouldn't be happy with using images of the interior of the workshop.
I do mean work (before and after shots) and workshop. I understand your security concerns, but you don't need to provide a detailed floor plan of the place, just something that shows you have the tools to get the job done and that it is kept clean and tidy. Take a look at
Kwik - Fit,
Stadium Garage (scroll down, it's parallax) - you can see that the garages shown look to be kept clean and tidy, able to undertake the work that you want them to; they don't show too much detail, but it's up to you. Look at the angle of the pictures taken
