(Oh, and in private flying there's no requirement for pilots uniforms...)
I got bollocked by my CPL instructor for turning up to my CPL skill test in cotton mountain trousers and a polo neck (my normal flying "uniform", albeit usually supplemented by either a flying jacket or a flight-suit).
I still passed.
Interestingly, said FI is now his school CFI and last I bumped into him there, he had turned up in jeans and a rugby shirt
We all have a personal rate of learning and progression!
G