I hate nights, some people love them. Generally very quiet, you get all day to yourself which is great but the feeling of the second night working the 6-7am rush is not great.
Shift patterns are amazing, I love it. Walking round Tesco with the place to yourself, doing whatever you want through the week without being confined to Sat/Sun like most of the unwashed masses.
Sleep is never an issue, except maybe before a night shift if theres outside noise.
You remain "mobile grade" with NATS so they CAN move you anywhere, but in reality once your valid unless you seek to move you will stay put. Dress code is informal unless you work at Swanwick where sandals and bermuda shorts are the uniform.