Can't go far wrong with popping into Performance Foods next to the Tesco by George st and having a chat with them. They generally know their stuff without bullshiting you.
It really does depend on what you want from the gym and how dedicated you are.
I take a protein shake after the gym or football because it helps with recovery but you can also bulk up from it if you take 3 a day. Creatine you need to be careful with. It bbasically stores water in your muscles...