A better bet for the Austin ambulance wuld be the 1:35 scale AIRFIX kit. Very detailed - as you'd expect - with various markings available to suit the theatre of operations. I saw a beautifully made model in a model shop in Cheltenham. Cost £27 or so as I recall
As a matter of interest, the last of the old Austin heavy ambulances soldiered on operationally until until the late 60's, certainly in Singapore where there was an RASC detachment from 25 Company operating from the BMH / Alexandra Hospital. 27 Company operated some from BMH Kinrara. Last ones I saw in the UKwere in the cast vehicle park at Warminster Workshops in 1970 from some TA unit down in the South West. If I remember correctly, they all had YF numbers, such as 77 YF 16.
I'd like to soo Airfix make my favourite of all, a Bedford QL. But I might get an Austin ambulance......