PaddyR70 - if that is an up-and-over garage door to your workshop, please get rid of it. My father's workshop was much the same and it killed him! Unfortunately due to sparks from metal cutting, wood shavings caught fire and he couldn't escape; OK easy now to call stupid but the ability to use that sort of door as a fire escape is virtually impossible in comparison to side hung doors.
As a further question I notice you have had the roof foam sprayed. I've heard that is an expensive operation - just what sort of cost was that on a per sq metre basis? One of the questions that comes up here quite regularly is how to cope with condensation on a metal roof, and spraying on insulation is suggested with an appropriate sucking in of breath on the cost!!
Rob