Will she be living there? Will it be her home? Are you planning a life together and this is the next step; moving into an owned home rather than rented and renovating it to make it suit you?
If this is a joint home for you to spend your lives together, then why does she get no say?
If you were a man, and the girlfriend was posting saying "My partner and I live together in a rented house but he wants to buy somewhere. I can't afford to buy so he is doing it himself, but we're both moving and it will be our home. He's now saying that it will be his house and he as final say on everything". Then I think the responses would be quite different.
She'd be getting told to save up her own money, don't rely on this man to keep you safe as if he ends it you'll find yourself on the streets with nothing and no rights. Or she'd be told to insist on paying toward the mortgage and have an agreement that she gets a share in the event of a split.
Think about what happens when she leaves. Are you telling her she needs to have savings as if you split, she will be homeless? Or are you discussing contribution towards mortgage for a share of the house? Either one is fair, but she needs to know exactly where she stands, especially if you involve her in decision making.
If it is your home, and she makes no financial contribution and you intend that she will have no right to the property then just make sure she knows that. If you go on to have kids, and she sacrifices her career etc then the situation will change but plan for now.