Medicals used to be don by CAA medical branch down at Gatwick.
However, in April this year NATS brought in its own occupational health team which is based at Heathrow.
Hence you are being done at Heathrow.
No nasty surprises, chest x-ray, urine sample, lung capacity, eyesight, hearing, height, weight, general physical condition, ECG.
Think thats about it,
Good Luck
------------------
Turn left heading 230, close from the left, report established