As a director and shareholder of your own limited company, taking a loan from your company (often referred to as a 'Directors Loan') is allowable, though it is recommended that you document the amount, repayment amounts and reason for the loan. If the amount you take exceeds £10,000, tax is potentially due on the balance at 25%, if not repaid within nine months of the business year end. This would be repayable however, when the loan is repaid.
Furthermore, if the amount exceeds £10,000 unless interest is paid by you on the loan (at or above 3.25% for 18/19) it will also be treated as a benefit in kind payment. Benefit in kind is taxable as a personal tax liability plus the company is charged national insurance.
To repay any loan, just make a payment back to the business bank account using the agreed payment schedule.