The main advantage of the self-employed (or sole trader) status is that it is very easy to set up. You are then considered as a sole trader because you are the sole owner of your business.

You can register as self-employed through an online form and you will receive your UTR number in a few days. https://www.gov.uk/register-for-self-assessment/self-employed

You will have to complete an annual self-assessment tax return, a process that can be done online on https://www.gov.uk/self-assessment-tax-returns

Moreover, being your own boss means that you are completely flexible, thus you can work whenever and wherever you want and for whomever you want. You can thus make your own schedule.