Hi palemazy
First the good news, your CB ESA will stay as it is ☺️ and will not be converted to UC, if you are in the support group you should be placed in the LCWRA group on UC.
Now the not so good news 😱 when you apply for UC DWP will work out your allowance as a couple, your CB ESA will then be deducted £ for £, there is no permitted work, if you are placed in the LCWRA group then you will be entitled to a Work Allowance, there are two rates, high and low depending on your circumstances, you will also get a Earnings Taper of 55%.
We would advise you to seek help from your local Welfare Rights Organisation, they will be able to take all your circumstances into consideration when giving you advice;
advicelocal.uk .
Gary