The purpose of a director's loan account is to allow you a straightforward way to either subsidise a cash-poor company with personal capital (thus becoming a creditor to the company), or to take money out of the company (e.g. to cover personal living expenses whilst you operate the company, and thus become a debtor to the company).
The purpose of the latter is because you (or other directors) may not want to finalise the withdrawal you make (via salary or dividend) until later - for example, the dividend will be determined later by the actual profitability of the company.
Until the profitability is clarified, you remain on the hook personally to repay the director's loan you've received. If the dividend (i.e. your share of the profits) later exceeds the loan, then you'll simply be paid the net amount (i.e. the gross dividend minus the total loan you've already received).
If the dividend turns out to be less than the loan, you'll have to settle the debt with the company by putting money back in - perhaps by liquidating your assets, or taking out a personal loan at interest. Also if the company folds and owes creditors (whether other directors, or suppliers, etc.), you'll be personally liable to make good the director's loan you received.
But in the meantime, you can fund your standard of living based on your rough expectation of profitability, and leave the detailed accounting and taxpaying until later once the whole year's trading is concluded.