hi
dont take my word for it but on jobs i have done, i have been told that if it is built 5 metres or more from the main building. ie your house then building regs dont apply because it is classed as an out building and hence planning permission and such like dont apply, on the job i did the building inspector didnt bat an eyelid because of the 5 metre rule, and the garage was built with out a hitch!
hope this helps
richard