Knocking down and replacing a garage - cost

[NoTeaForMe]

We are looking at knocking down the garage that is separate to the house and re-building it next to the house so that we can also go above it to create another bedroom. Just average single garage sized. Any idea on cost? I know it’s a big of a tricky question, just a rough guide?

£10-£20k depends on access for machinery, material (stone more than brick), roof materials, internal finish.