Fuss about nothing. No one has ever turned up for work in clothes that offend me. I wear shorts when it's warm, hoodies when it's cold, full highland dress on St Andrew's day and baggy, comfy stuff on a night shift.
The jobs I had pre Nats all had a dress code. As a hotel manager I was always in a suit and when I worked in a supermarket they provided uniforms. I really don't mind a dress code.
I work at Prestwick and the Nats staff are the only ones who don't have a uniform. Security, restaurant staff,cleaners and of course the RAF are all smarter than the ops room staff. Nats could always spend a few quid and get us all a few branded shirts,t shirts etc.
My normal dress is jeans,t shirt and trainers and I don't intend on changing that. On the very rare occasions that I represent Nats outside of work (did a school visit last year to do a presentation on ATC, fam flights etc) I smarten up appropriately.