I am on the extending houses thread but we are rapidly cooling on the idea as it apparently costs £35k to extend our kitchen by 3.6 x 4.5 m (excluding the units and appliances). We previously looked briefly at having a garden room (not a shed, but one of those quite plush units with insulation, heating and lighting) which we could use for music and thus remove the need to change our dining room into a music room. We have plenty of space in the garden.
We discarded the idea as some of them can cost in the region of £20k. However, this is now looking like a bargain in comparison to the extension costs. Does anyone have one and can advise on how they find it - do you actually use it if you have to go into the garden to get to it, is it hot/cold, how about noise escaping from it? Am also thinking that it would be a cool place for the boys to hang out when they hit teenage years.