The dates of the Y6/7 induction days and Parents meetings are on the Parents calendar on the school website. These meetings tend to be late June/ early July to avoid clashes with KS2 SATs and to allow time for families Appealing for places at the school. There will be forms for parents to fill in and you will be sent a Welcome Pack by the school with details of uniform etc. The primary school will probably be starting to transfer information about your child to the new school too.
I live in Bristol too and had started to become concerned by the same thing. I had heard of other parents at other schools in Bristol receiving welcome packs. I phoned the school today (CGS) and the admissions lady told me that they will be sending out the welcome packs after the bank holiday to tie in with the second round. I also asked her to check that my dd's name was on the list and it was (phew)
Induction is normally July but some schools have things before then. At some point in May or June you will probably get a bundle of forms to fill out and uniform lists / school-home agreement etc to sign.
If you are worried they haven't acknowledges your reply, you can always email to check they got it O.K