I requested a copy from the school when my daughter was about thirteen or fourteen - after all contact with her had ceased due to alienation. Her form teacher or head of year, Mrs White, refused or at least ignored my letter, so I wrote to the headmaster. This prompted Mrs White to "ask permission" of my daughter to give it to me. My daughter then agreed apparently - (what would she have done if there was anything bad in it one wonders). So a teacher I've never met chose to go out of her way to try to deny me a copy of the school report, or at least make it more difficult - I didn't go to parent teachers evenings by the way because of the hostility with my ex. and I knew my daughter was doing exceptionally well anyway. I have no doubt the teacher knew through gossip the reasons used in court to justify my exclusion (all false or trivia I hasten to add).
In fact the head of the court welfare service office I was sent to during the court battle over contact used an argument to my solicitor saying that my fighting for contact was/might be jeopardising my daughter's education, (I think/hope the opposite was true - my fighting to stay in her life made her feel valued). Maybe the same teacher had been in touch with him.
Anyway, all this prompted me to seek out our governments advice to schools on the subject of giving parents their child's reports. I can't find a copy at the moment but if I do I will post it for you. However, if my memory serves me right, it doesn't seem to put any great obligation on the schools to provide us parents with their reports, whilst not seeking to deny them either, if you see what I mean.
Still, as I've said already, parents in the UK have "no" rights, constitutional or not (we haven't got a written constitution of course but that's a different argument and by the looks of it yours isn't giving the NRP much family life protection anyway - is that fair?).
ATB, Graham