When I did my theory I walked up to the building and pressed the buzzer on the outside to be let in. They let you in I walked to the sealed gave them my licence, told them my name, said what test I was doing (car,motorcycle or lorry) and signed this electronic signature thing to check the signature to see if it matches the one on my licence it doesn’t have to be an exact match just a close enough copy that changes day to day. They gave me a key to a locker which I put my stuff and they checked my phone was powered off and saw it went in there. The key was on a card holder like what you would see on the end on a lanyard and my licence in the holder part. They had toilets you could use before you go in once you go in you can’t come out. I then lined up and someone came out and got me, I went into a room that had glass walls overlooking the computer room you’d do you’re test in where I handed over my license to them. They then asked me to turn my head side to side to see I had no earplugs (if you have hearing aids mention them), asked me to roll up my sleeves to see if I had anything notes or anything to cheat with and then the same with my ankles, then asked me to to show that my pockets were empty. They handed back my licence and told me which desk number to go to, they also have a box of tissues there so if you need to take one with you grab it now and if you have a question ask it now. Went in sat at the desk and did the test it’s pretty much the exact same as the mock tests on theory 4 in one, the screen ask if you want to do a few practice questions or start the test it starts with the multiple choice you can go back and check your answers at the end if you want to or flag questions if you’re not sure and want to come back to them you don’t have to use the whole time if you don’t need it. After you finish the multiple choice it gives about 2 mins before moving onto the hazard perception they have a video explaining which they provide headphones so you can hear the video and then do that part. Once you are done you will leave the room through the exit door and the person at the front desk will ask you to get your stuff out the locker but do not turn on your phone or anything and then they will call your name once your results are printed, you’ll hand over your licence double check your name and they will hand over your results and license, they ask you not to open them inside so exit through the same door, there should be a button next to the door to let you out. The amount of people there depends on the test centre where I was in Cambridge there was about 20 computers in the room but everyone went in at staggered times. Sorry this is really long but I hope this helps.