You can work while receiving SU. However, you will be subject to an earnings ceiling, which is calculated on a monthly and an annual basis. If you exceed the annual earnings ceiling, you must pay back some of your state education grant and, if any, loan. You should keep an eye on whether you stay within the annual earnings ceiling. To calculate your annual earnings ceiling, you can use the income calculator.
To calculate your annual earnings ceiling, you must add up the 12 monthly amounts you are allowed to earn. Your annual income must not exceed the annual earnings ceiling. That means that it doesn’t matter if you earn a large amount one month and less the following month as long as you don’t earn more than the annual allowed amount.