(speaking from experience) after half a year or so, you indeed will have some free time to do your own things - research, sidelines, etc. however, if you are not cut out to be a teacher, life will be pretty miserable for you - bullied by "old birds", heads, technical officers and students.

if you believe you are the kind who can figure things out, and smart enough to find ways around to avoid the usual bullying and politics, you should be quite ready for the work-life balance you are looking for.