Active job

Garage Conversion

Want to convert our garage into a granny flat/studio unit with kitchenette and basic bathroom-Have family moving back in October this year so would need to be done by then. Size is 6.6m wide x 6.2m long, it is brick 3 sided. It already has windows in it as I believe the previous owner planned to do this but never got round to it. Firstly want to know if this is even possible and if so what's the process, assuming I may need to get some plans done, consent? Attached photos of garage right now. Thanks.