Mistakes happen. And if you’ve inadvertently added the wrong permission (category) to your Interim Permission, then all is not lost. You could simply apply for a variation of permission via the FCA’s website.
However, you may not need to take any action.
The FCA should have written to you and advised when to apply for full authorisation, and by completing your authorisation application this should remove any ambiguity in your permissions.
In addition, the FCA ‘carried forward’ permissions (categories) from the old OFT Consumer Credit Licence. So even if you did select the wrong permission,the FCA will be aware and will know what your permissions should be.
So, in short, you don’t have to do anything until you actually apply for full authorisation!