Try to look at a few different websites of your local sport clubs for starters. Contact the sports department of a good university for a few more specific recommendations etc. Also you can also email a couple of accredited local tennis coaches and the like for some more help in finding a number of suitable sport placement options as well. They should be able to offer advice and resources.
Local primary and secondary schools may also have open teacher vacancies for wannabe talented sport coaches. I would definitely begin your placement search by enquiring about the careers at primary schools nearby.
You also can check on the school website, phone up or perhaps email someone at the school for a few more additional details. Make short notes on your findings in case the job listing suddenly disappears tomorrow. Pay very careful attention to the wording of the job advert and also prepare a complete short list of your job related skills to have at hand on a separate Word document. Ensure that you have read it properly looking at the job related skill criteria which forms a part of the original advert. Also be sure to look very closely at your resume and see if you can then make any corrections to it. List all of your accredited qualifications in sport too.