school assemblies - do they have to go?

I don’t want my child in school assemblies. Do I have a say?
Absolutely.
Schools have a statutory obligation to perform what the law calls a ‘daily act of worship’ and, in the UK this needs to be ‘mainly of a Christian nature’. Now, in practice, nobody ever actually checks up on or enforces this and in today’s multicultural and secular Britain it is true to say that the overwhelming majority of schools are probably interpreting this statute to fit their own context.
However, every parent has the right to withdraw their child from the act itself and it is the school’s responsibility to accommodate this wish as well as to provide the pupils with an activity and the appropriate level of supervision.
Your school should be able to provide you with a copy of their own collective worship policy and tell you about their own daily assemblies.