When I became a Boy Entrant in 1952, this was my 1st 'employement' and I remember that my NHI stoppage was 1/9 a week. I have no idea what was contibuted by my 'employer'. In the RAF we never had the card with stamps on, and these had been discontinued by the time my service ended.
As for Income Tax, I started paying that at in 1954 the rate of 1d a day when I was promoted to SAC on 11/- a day. As an LAC on 10/- I was apparantly under the threshold.
But lets face it, nobody joined the military to get rich.