We usually have two social dancing sessions in an evening:
Between the Level One and Two classes
8.45pm - 9.15pm
After the Level Two class
10.00pm - 10.30pm
Everyone is very welcome to attend either or both.
Feel free to ask anyone to dance and certainly the teachers, who will be delighted to help out either with advice or a dance.
Whilst there are no rules exactly, usually if someone asks you to dance it is considered polite to accept. Furthermore it is good to circulate, so try to limit your time with one person to one or two dances at the most.