DS1 is going into year 10. I know the subjects he'll be studying but not which exam board for any of the subjects. Is it normal not to know? I had a look at study guides in WH Smith and there seemed to be different ones for the different exam boards. Would I be one of "those" parents if I asked the school?
Normally your DS will be told within first few lessons (or it will be on the school website); however there may be subjects where the decision has been made as some specs have only just been published and due to the lack of time supporting texts available
Just ask the school. Although I think it can be better to wait until the school advises the kids to buy the guides, at a point when the kids have had enough teaching that they will have enthusiasm for engaging with the material.