I’m going to Mexico soon, should I buy pesos or USD? Im thinking of taking £500 would it be enough for a week of activities?
What part of Mexico? They're more likely to take dollars in the beach areas of Cancun. Otherwise, use your ATM card to take out pesos. Do NOT take that much cash with you. Take it out as you go. The cheapest way to get money is usually through the ATM machines (which are everywhere) and it's the safest way. How much you need depends on where you're going to be and what kind of activities. Things are more expensive in the resort communities, and if you want to do things like parasailing, you could easily go through 500 pounds in a week. If you're in the colonial cities, a lot of things are free and food is pretty inexpensive. I can't imagine spending that much.
That depends upon where you are going.