Hi, I'm from the RVC
I don't have a written budget plan, but I use online banking to limit how much money I have on my debit card. If you create a standing order, they will do it automatically each week. I also send slightly more than I need every week so if there's an emergency, I still have some money left!
In terms of how much you need, I think at the end of the day, it depends on how often you go out and which sport you play. Some sports are very very costly (Polo for instance) while others are relatively affordable. Some ask you to pay a lot at the beginning of the year as subs, and others have higher weekly costs. Anyway, I can't really tell you a specific amount as it all depends on your lifestyle! But for myself, I started out with about 70 to 80 a week till Christmas (books and alcohol are costly!), but I managed with 50 a week at the end of the year. If you have any specific questions, PM me