More places do seem to be available at girls' schools than boys' as girls often want a move to co-ed. Entry to co-ed schools at this age can therefore be more competitive.
There is some movement between the London day schools, but remember places are still seriously difficult to win, and it is a good idea to have a back-up plan.
Registrations should be in by the end of September of Year 11. This will include a personal statement and CV for some schools. Assessments take place during November and offers are generally made at the beginning of December of Year 11, but will be conditional on GCSE results.