For simplicity you may find it beneficial to have self employed casual workers that you pay as a supplier rather than a temporary worker. However, you will need to pay them more to compensate for their additional overheads of being self employed. Also, for some businesses some employees can find being self employed overly complex resulting in you having difficulty finding staff.
All swings and roundabouts, and as I say, start with the above link.
HTH,
Shaun.
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Shaun
Responses are not meant as a substitute for professional advice. Answers are intended as outline only the advice of a qualified professional with access to all relevant information should be sought before acting on any response given.