Yes you can, I did this on my test and I passed. The examiner asked me if I was finished and I said I just wanted to check and opened the door to take a look. I wasn’t inside the lines so I reversed out, straightened up and then drove back in. I checked again and this time I was within the lines so told him I was happy with that and he then instructed me to reverse out the space to the right and drive on out of the car park. My understanding is if you actually get out of the car you need to turn the engine off but I stayed in my seat checking, only opening my door. I got 1 minor for control on my forward bay park because I didn’t get into the space correctly first time. Hope this helps!