The information you provide within the SA302 calculation will determine how much tax is due. This calculation will then apply any tax already deducted and leave you with a balancing payment (if there's any tax outstanding) or a repayment due (if you've overpaid in tax).
If your total tax bill is over £1,000 and less than 80% of your income is taxed at source, you'll need to start making payments on account. This means that you'll pay tax in advance for next year's tax bill. You can read more about this in the KB article When do I make payments on account.
In 2022-23 your total tax bill was £3,000 and less than 80% was taxed at source.
You've already paid £1,800 so your outstanding payments are as follows:
Payment due by 31 January 2024
Payment due by 31 July 2024
Payments on account will include Class 4 National Insurance Contributions where applicable, but not student loan repayments or Capital Gains Tax.
You can read more about payments on account in these KB articles: