The taxable turnover threshold which determines whether a person must be registered for VAT , is at £85,000 hence you are well below the VAT threshold unless you have other businesses – hence you dont have to be VAT registered and you have to tell the sports site.
Note this VAT threshold is per person (not business) – ie self employed/ company etc ; if you have other trades and you exceed this threshold then you may need to register for VAT.