I left as a DC in 2015 due to burn out in my ten year career. 80+hr weeks were normal.
Working seven consecutive nights of call out once a month, ten consecutive night shifts twice a year, the full shift pattern of 6 on 4 off on CID or 5:2, 5:2, 10:4 on major crime and specialist departments is normal. And you don't get extra money for being a detective.
You'll need to be as fit as a uniformed officer, you'll still end up in the odd fight and dealing with violent offenders frequently so you'll need to be prepared for that.
It's fucking exhausting. There are some epic days being a copper, but for me, in the end, they didn't outweigh the cost of my mental health, physical health or total lack of balance in my life. The idea of starting it again now in my 40s makes me want to cry just remembering the constant stress and fatigue.
That said, I really miss elements of it. The absolute satisfaction of a bloody good investigation resulting in a brilliant arrest, a highly enjoyable interview and subsequent authorisation to charge and remand of a serious high.
It just wasn't enough in the end.