Hello crazymum53 - I am a Computing teacher and was part of the pilot for the GCSE in Computing, so have been teaching it for the past 4 years.
Firstly, with regards to your comment: OH has degree in Computer Science from an ex-poly, so would have expected teachers to be a bit more knowledge than him. - I agree that you should expect it - however, this course has been pushed onto existing ICT teachers who will have a degree in an ICT related subject but not necessarily a Computer Science degree. It is like saying to a German teacher that they suddenly have to teach GCSE Spanish, even if they have never covered the language before. I am lucky as I have a Computer Science degree but not many do and Gove is only putting aside less than £3 per IT teacher for further training.
Secondly, maybe I can answer your DD's question, The language they are doing is called Python and my OH wanted more information about the type of language this is and what it is used for Python is an open source language that covers two paradigms; Object Oriented Programming and Procedural Programming. Therefore, it is a good language to start with (and can be used on a Mac and a PC) It is used in industry in a wide variety of ways - organisations such as Apple and Google use it for their backends, for example.
As it is the first year of teaching it at your DD's school, I would question whether you are prepared for her to be a 'guinea pig'. If you are (and someone has to!) then it can't hurt asking your DD to have a quick chat at lunch or in lesson with the HoD or another ICT teacher, whether or not she can apply and what the reasoning is behind it all.
Thirdly, They've been very clear that computer science is much more maths-orientated than ICT There are no actual mathematics (for want of a better word) in the GCSE Computing course per se, but there are logical functions and some basic binary conversions - all of which are done without a calculator and you don't need an A grade in Maths to succeed. The correlation that is there, is that if you are 'interested' in Maths, than probably likely to be interested in Computing. I have had students get a C grade in Maths but an A* in Computing over the past couple of years. However, there are exceptions both ways. I would actually say that Physics is closer to the GCSE Computing with regards to the electricity topics with circuitry etc. Teachers are using Maths as a guideline due to the unknown with teaching a brand new GCSE for the first time.
Have faith in the IT teachers though, they will do everything they can to get your DCs the best possible grades they can - including going on training during their 'holidays' which has been happening for the past year now.
I hope this helps and let me know if you have any other questions. Good luck with your DD's options.