Op you've had lots of good information on this thread.
It seems that unless you move her, your dd is going to have to do this GCSE. It's not something I've heard of often, but RE as a full or 0.5 compulsory GCSE is not unusual. IME it is then an extra to the normal options, taught in maybe one lesson a week.
You need to find out if this is the case here. Assuming the usual compulsories of Eng X 2, maths, science X 2 or 3; does she have three other choices or only two bc of Citizenship? And what's the "wiggle room" for a 10th subject? A twilight after school? Triple science as a 10th in the same time as double?
Are there other compulsories - hist/geog and/or MFL? Worst case - her nine are all compulsory - English X 2, maths, science X 3, history or geography, MFL, Citizenship. This seems unlikely tho as then no one would do DT, computing, PE, RE, music, art, drama...
So I imagine she will have at least one choice, which is not that unusual, and maybe (with the wiggle - or if. MFL is not compulsory) she'll have two - which is pretty much as many as you get in most schools.