There is a whole guide on this:
https://assets.publishing.service.gov.u ... .0-ext.pdf
Company directors are NOT necessarily self-employed. This is a common misconception. However, in both cases, you need to file self-assessment. If you are not registered as self-employed with HMRC, you must rely on your company tax year and ignore the normal tax year period. You will need to submit CT600 rather than the self-assessment.
If you are yet to produce an account, then you cannot use your current income from your company towards evidence of finances and you
may fail to satisfy the requirements under category F or G.
Advice is given based on my personal research and experience only. Do NOT contact me via private message for immigration advice