The OP shouldnt have to ask if he wants something. He obviously works hard so is entitled to a present for himself. Isn't he?
I never said he should "ask", I said he should discuss it with her. That means explaining his feelings to her (he feels like rewarding himself) in a way that makes her understand where he is coming from. They might agree that they both deserve a reward for their hard work and have a budget of X this month for that. After that they can revert to their low-spending plan. It's not really something that you and I can decide for them, but what I am trying to say is that the foundation of any relationship is good communication.
As for whether he is entitled to a present, it's not that clear-cut. If they agreed to take on lots of debts and pay them off as quickly as possible, his "presents" might be undermining their long-term plans. She might be refusing herself the pleasure of rewarding herself with something, so how is she going to feel when she finds out he's done that?
From what I know of women, I seriously doubt she would spend £1000 on something without discussing it with him, so it makes sense for him to do the same.
Edit: See his post for confirmation of the above