Garden room advice

[Fushia123]

Our DD (23) will be returning to live with us for at least a year. She has her own bedroom but the house is pretty small and I want to try and prevent us feeling as though we are living on top of each other. We have a side and back garden lawn and have been considering having a garden room with electrics built on the side garden. She could use it as a snug/study whilst home, and we’d hopefully have a lovely extra room when she moves on. Still not 100% sure about whether we can afford this but it seems like a reasonable solution?
I would welcome any advice about how to go about this, any recommendations from those who have done it and what pitfalls and difficulties to consider. Thank you

We got a garden room installed in our side garden recently.
There was a lean-to type structure there previously so very easy for us as we used that footprint.
We have electric installed with recessed lights and fully insulated and plastered. We love it, an extra room for the house and we have a largish garden so was great to use during the recent lovely weather when we had friends over for a bbq. It is south facing and doesnt overheat like the previous lean-to(previous owners called it a conservatory, it really wasnt)
Go for it we love ours and are looking forward to getting great use of it.

Thanks for your message - definitely food for thought!

Hopefully someone can advise better, but I understand there are different building regs for using it as a bedroom (and presume en suite?).

Would you need planning permission?