if your med is with nats in swanwick prob same day cause i had to be referred for a second opinion to the caa, so i assume if its all fine they tell you there and then. if however you do need to go to the caa again they would grant you the certificate there and then when you pass the examination.
its not as stringent as maybe i thought it would be, just try and stay relaxed for the ecg. and theres no blood tests at all
good luck simfly