Hi and Welcome to the forum, you might want to have a look at the following FAQ which explain where everything is
Welcome to Benefits and Work As long as your ESA is
completely contributory then it does not matter how much you have in the bank or how many hours your partner works. However, it is possible to have contributory ESA with an income-related top-up (due to low income). If this were the case it would be important to notify DWP if you access your savings and/or your partner goes back to work.
If you are in any doubt about the status of your ESA you should contact DWP in order to avoid problems later!