Thanks for all of your replies, I didn't anticipate this many so soon.
There seems to be a big range of prices for technical support out there.
Just to add a few details to the support we currently get. Our technician is available by mobile phone and e-mail (straight to his phone I believe) all day every day and will always come in if we have an emergency and hasn't yet charged anything extra for these ad-hoc visits. We've also used his knowledge a lot towards furthering the development of ICT in the school - as he visits many schools he sees much more different technologies than we do.
Of course, server installation (happening soon ), network and av installation are provided at additional cost.
We have 7 classes, approx 210 pupils, 30 staff, approx 50 desktops, 10 laptops (soon to be an additional 45 laptops ) an RM CC3 Network (soon to be decommissioned and a vanilla network put in its place) and prometheans in every classroom.
This is good research and I will compile all of this data for our governors.