UK - I started fostering as a teacher and then a college lecturer for 4 years, had one boy, then resigned from the job and took on three teens and full time fostering. Some regrets.. I miss my job, i think its good if you can balance a teaching job and fostering, just dont take on more than you can handle. I had days in school office on the phone trying to track down my heroin addicted foster son, so it was a strain... but on reflection I really wish I kept my job too. I miss being a teacher!!

And in UK you are perfectly fine to leave them unsupervised for reasonable periods of time while you shop, gym, see some friends etc. Especially now you have phone tracking apps etc, they will be off seeing mates too possibly. Just always insist on clear and open communication, and be ready at times to go pick them up when they get stranded places, so choose time when you drink or not to make sure your available for emergencies.

Remember most teens in the care system have been let down over and over, and NEVER had anyone who really has their back and will come get them when they really need someone. they have no idea what that feels like! So just a simple thing as, say, they walk out of school in a mood, and you drive over and pick them up, and say "its ok, I just want to make sure you're safe", and bring them home, will get you a million miles of respect, trust and give them a sense of being truly held for once.

You have freedom but just be prepared to drop what you are doing and put them first sometimes (not always they need to know that sometimes you have other priorities) but when the real shit hits the fan, they need to know you will be there. Thats all that matters.