Depends on how old you are. Black jacket should be worn with white stock, tweed jacket should have a coloured one (but this is normally worn for cubbing), both with long boots, and those under 16ish should be in pony club tie (if member)/tweed/short boots.
I used to wear a blue jacket/long boots/stock from about 12 onwards - I think it's ok for U16's to wear this because;
A - Hunt jackets are much warmer than tweed
B - Stocks support the neck in an accident and a tie doesn't
C - long boots would protect your leg from a kick much more than your jods!
I never hunted when I was under 16 so I just put what the general rules are according to what I've seen. I think it depends on the hunt, really. As you're 16 I'm sure black jacket/white stock will look very smart. Have fun!