Hi there,
I agree with Bobo - Clinical Sports Medicine is an essential text if you want to be involved in sports physio.
Another asset (particularly for someone in your financial position) is the huge amount of free information online. As well as YouTube, a good blog for you to check out is
www.TheSportsPhysiotherapist.com (yes I know, I'm plugging my own site) - which discusses the aspects of being a 'sports physiotherapist'.
I would advise you to take the position, as sports physiotherapy offers an amazing experience.
I really hope this helps, and good luck!