Our school has a uniform - in local terms it's pretty strict. Blazer, shirt and tie, with optional jumper, cardigan or sleeveless jumper. Black bottoms, it can be trousers or skirts, black shoes.
It's mostly stuck to and mostly it's proper shoes or boots. They have occasional monitoring weeks where they have a good look at what pupils are wearing and let them know if anything isn't up to scratch - no-one gets sent home, no-one gets disciplinary notes. A few kids don't have blazers but wear the jumper with a jacket and take the jacket off in school. Pupils can take off their blazers if its warm without permission.
Hair colour/length is not an issue.
I've added a photo from the school website, I am sure the skirts would be banned in some schools from what I've read on the thread. I think that photo is fairly representative. There are some that are more way out in terms of hair styles and some with more conservative skirt lengths or trousers.
The school has very little in the way of discipline issues and is very successful academically. I accept that a lot of that is down to demographics but some is just down to not trying to score points or make a mountain out of a molehill.
I've said already I'm not sure a shirt and tie is necessary but I equally don't like the polo shirt and joggies suggestion - especially for high school, but then I've never been a joggies fan tbh. Two boys I've got to teenage years with no full length joggies ever. Jersey shorts are a different matter :o