Why are you paranoid about it?
I had my medical in April for a signaller job, it was quite straight forward. You have to fill in a medical history form. They put you on a breathalyser and you have to blow 0. They take you to the toilet and you have to do a drugs test. They do a colour-blindness test with you where you have to read the numbers in a load of coloured circles, an eyesight test, a hearing test, a BMI test and a blood pressure test. You have to declare ANY medication you have taken in the last 2 weeks to be sent off with your drugs test - don't worry about this, as long as you declare it. They will ask you for your medical history and they will write anything down, I had 3 operations in 2011/12/13 - did not have to declare these and they did not write to my doctor. I guess they will only contact your doctor if you declare something that may worry them.
Hope this puts your mind at rest a little bit. Good luck.