I am a SENCo at a primary school and we have a child in year 5 with Noonan’s Syndrome. I was wondering if you could provide me with support or advice on how best to educate her on what to expect in puberty and teenage years?

We aren’t aware of any specially adapted resources in primary school in preparing for puberty (only the standard resources given to all children). In preparing for secondary school, if she has learning difficulties and/or autism and you feel she needs a more simplified version of puberty education, her mum could ask for this at the EHCP annual review and the school should be able to provide it. There are also sexual health charities who can support, such as Dhiverse, who have a programme for children (aged 11+) with learning difficulties or autism called ABC: https://www.dhiverse.org.uk/our-services/learning-disabilities-difficulties/. They produce a free booklet and a leaflet which is more simplistic with pictures and they run a workshop programme. You would need to search online to find something similar in your area. Mencap also produce a guide (Sexuality and Relationships Resources) which contains information and links that might be useful.
Girls with Noonan’s Syndrome tend to have delayed puberty and start their periods later. This is less so if they’re taking growth hormones, but even with those they will start their periods later than their peers, which could potentially cause stress if she doesn’t realise beforehand that this will most likely be the case. NS girls also tend to have heavy periods because of problems with blood clotting. There are options to deal with this that her mother could discuss with her GP if it causes issues with her school attendance and/or participation in activities.