Garage Unconversion

Hi, I am looking to buy a house where the integral garage has been converted into a room (solicitor is looking into planning permission / building regs info). Garage door still exists but a stud wall has been placed behind it. My question is I want to convert this back to a garage do I have to get building regs involved? Additionally I assume it is just simply a case of pulling out the stud wall, the current garage door is an up and over but I want to change this to a 50/50 split pull out door. Hope the above makes sense and thanks in advance.