All she could do is pass your request on to the doctor or nurse for them to deal with it. She cannot add or remove items from your prescription nor vary the amount or dose. Thankfully.
They need to have the nurse prescribers course and can only prescribe a limited range of meds, mostly inhalers for asthma /copd, complex dressings, stoma products, and skin care items. Some with the advanced prescribers/practitioners course can do more but usually only in a hospital setting.
I don't think that's true rowan - once you are a prescriber, you (in theory) have the ability to prescribe the whole BNF
However, your employer may limit you or you may wish to limit yourself
All nurses that belong to the RCN have professional insurance I think unison provides the same, they will also be covered by their employer. Items on the nursing formulary are considered low risk. Even when I was nursing we had a limited formulary that saved us bothering the junior doctors for things like simple analgesia, laxatives and one off low dose salbutamol nebulisers. Nurse prescribing was Just starting when I left.
The key phrase is "within their area of competence,". This generally means nurses stay mostly with their specialities and the content of their prescribers training.