My building is also 7 x 3 Metres so I interpreted the Regulations:-
Building a detached garage of less than 30 square metres floor area would not normally need building regulations approval if:
the floor area of the garage is between 15 square metres and 30 square metres, provided the garage is at least one metre from any boundary, or it is constructed from substantially non-combustible materials.
So, my building being mainly of wood construction has the requisite 1 Metre Clearance at the Property Boundary.
P.S - One of the advantages of having a 1 Metre Clearance all round is that you can carry out any maintenance from within your own property and don't have to worry about gaining access from a neighbouring property.