the esa rules on permitted work (and you need to check this type of work is permitted)
The Permitted Work rules
Under the Permitted Work rules you can:
* work for less than 16 hours a week on average, with earnings up to £93.00 a week for 52 weeks
* work for less than 16 hours a week, on average, with earnings up to £93.00 a week if you are in the Support Group of the main phase of Employment and Support Allowance
* work and earn up to £20 a week, at any time, for as long as you are receiving Employment and Support Allowance
* do Supported Permitted Work and earn up to £93.00 a week for as long as you are receiving Employment and Support Allowance, provided you continue to satisfy the Supported Permitted Work criteria