The Quick Answer
The Coronavirus Business Intervention Loan (known as a CBIL) is a loan due by your company first. If there are insufficient company assets to repay the loan in full any shortfall up to 20% may be claimed personally from the shareholder or director that guaranteed it.
The answer in more detail
When the bank lend your company money under the CBIL scheme they will ask for a personal guarantee from one or all of the company directors.
If your company closes, for example due to liquidation, and there insufficient assets the bank can ask you up pay up to 20% of the loan back but no more. Additionally the bank are not allowed to take your main home called your principal private residence as security. Any shortfall on the 80% of the loan is paid by the Government.