As previously advised, use amateur games for a while. If you take to it and like it, you will soon realise that this 'hobby' can become very very expensive
. Full Pro bodies cost from 2k upwards, and a set of decent fast lenses not far behind(each), but look on fleabay and dont jump in at the deep end immediately. If you decide to buy Pro gear, consider last years bodies for starters, they will be much cheaper and will do all you need. However, a decent body will show up the shortfalls of cheap glass, so its a catch 22 situation, and IMO theres no substitute for good fast glass.
Dont be put off by your results if they are not as good as you hoped for at first, practice, followed by good kit will make massive improvements. Post any shots on here, good or bad, and see what people think, there are enough folk on here who will give you advice on how to improve or what went wrong with a particular shot. I assume you have a basic knowledge of shutter speeds and aperture etc and how it effects your pics, if not, maybe get a book on sports photography, or check out the many internet sites re this.
If you get in with a club, whether it be amateur or pro, ask them for help in getting accreditation from the RL, its always better coming from a club rather than an individual.
Good luck anyways, and hope to see you on the touchline at a game near me soon,
THE HOOF