As I remember from my days as a tester, the doors have to open, although they don't have to be opened from inside, providing the outside door handle can be reached from inside the car. I remember testing a car where the driver's door catch was broken. I spoke to the senior mechanic, who consulted the M.O.T. rule book, jumped into the driver's seat, wound the window down and satisfied himself that it was possible easily to reach & operate the outside door handle from the driver's seat-the result: a pass (but a word to the owner...)
I learnt something that day........
Checking the wording of the current rules I note this: (quoted from the MOT inspection manual)
Driver and passenger doors must open from the outside using the relevant control. Driver and front passenger doors must also open from the inside using the relevant control.
The important word here is "relevant" and my senior mechanic took the outside handle to be the "relevant" one, in the sense that it was "relevant" to the door in question, not "relevant" to which side of the door it was. I feel this wording is open to interpretation.......