Sixth Forms! Any experience with City of London Freemen's and Notre Dame

[3Plumpuddings]

Ok, so this is early, BUT dd1 wants to move for sixth form. The above two are on the potentials' list, along with a number of others, and just wondered if anyone had any experience with them. Can they come and go at different times in between lessons etc, what the school is like in general please! Thanks in advance!