Children born between 1/9/2008 and 31/8/2009 must apply for a secondary school place in 2020 by Thursday 31st October. See details and online application form for Lambeth schools at https://www.lambeth.gov.uk/school-admissions/secondary-school-admissions-202021
Many schools have an extra “supplementary information form” that is sent direct to the school by a date before the 31st October.
The test day for schools using an admission test is on Saturday 9th November.
Deadline for primary school admissions is 15th January 2020.