Depends on the sixth form or college. I go to a sixth form and my sixth form is quite like school, just with a bit more freedom and responsibility. At my sixth form, we have a fortnightly timetable. I get 10 frees per fortnight. For each subject, I have two teachers and 9 lessons per fortnight (except for Citizenship, I have one teacher and one lesson a week). I don't have double periods of anything (thank god!). Each period at my sixth form is one hour long, and we have 5 periods a day, with a 20-minute break after period 2, and a 50-minute lunch, followed by a 20-minute form session, after period 4. Usually I have 4 subjects a day with 1 free, but on Thursdays, I have all 5 of my subjects. It can be hectic sometimes, but we're provided with a lot of support and the teachers make sure we're on track to get our targets.
We have a sixth form college nearby and it's a lot different to my sixth form. The college is definitely more lenient and a lot of students do end up skipping lessons as the teachers don't care as much if you show up or not. You're given a lot more responsibility and you're treated like an adult (you even call the teachers by their first name!). From what I've seen, the teachers provide more support at sixth forms than colleges.