[UK only. This does not constitute financial advice and is my opinion only. Right, that's the disclaimers out the way!]
To be absolutely clear that is not just £1,000 or above on football income, it applies to ALL income outside of PAYE you may bring in, you don't get £1,000 for refereeing, £1000 for buying and selling on ebay, £1000 for selling art and crafts etc.
If you earn over £1000 then you will need to register as a sole trader with HMRC and undertake Self Assessment each year. Record all your legitimate expenses associated with your refereeing, for example matchday and training kit, subsistence such as water or sports drink, 45p/mile if that is not provided to you etc. When you submit your return to HMRC, you can deduct the total of all those expenses from your income. HMRC do not require the individual items (unless you bring in more than £85,000, unlikely!).
Note there is a £1000 trading allowance, so if expenses are LESS than £1000, you can deduct the trading allowance instead of expenses. Worked example:
Example one.
Income £1,500
Expenses: £350
operating profit: £1,150
HMRC profit: £1,500 income - £1000 trading allowance = £500 taxable profit
So you will be taxed on the £500, the amount of tax will depend on other PAYE income and tax burdens you might have.
Example two.
Income £3,500
Expenses: £1,200
operating profit: £2,300
HMRC profit: £3,500 income - £1,200 expenses = £2,300 taxable profit
I would personally sign up to a fee free business bank account like mettle.co.uk from Natwest, which also comes with free access to sole trader accounting software freeagent. When you get your match fees, pay them into your business bank account, keep it all separate from your personal bank account, and record all income and expenditure in freeagent. Other bank accounts and accountancy software providers are available.
As the sole trader you can draw money out of that bank account to buy yourself whatever you want for personal use, in accountancy this is known as an owner drawing. Just make sure you leave enough in the bank for your tax bill. The amount of tax could range from 0-40%, so as a general rule of thumb I am retaining 50% of everything earnt over £1000 to cover any potential bill just to be safe.
Cheers, Tony