Rough cost of a single storey extension - north west

[RigglinJigglin]

As the title says, I'm prepping for preparing DH (if that even makes sense )

I want to get some builders in to quote for a single storey extension to add a garage, utility and small corridor on our house about 4m square. With the footings done in case we want to extend upwards at a later point.

Any ideas of rough costs?

That way I can frame it right!

I found a general rule of thumb of £1,000-1500 per square metre has been quite accurate. Lower end for double storey, higher end single storey. Anywhere between say £16-24k + VAT??

Thanks Mandy, that's helpful!