Paying capital gain tax in advance

Hello. I am curious if there is a way to pay the capital gain tax for 2024/2025 tax year in advance. I have worked in UK for 5 years and thinking of permanently leaving UK, i.e. permanently going back to my country South Korea. Before moving, I sold all my stocks I had and I would like to send all my money to my Korean bank acount. The problem is the tax for the capital gain of the sold stocks. I sold it this month (Aug), so its tax should be payed in the 2024/2025 tax year, i.e. after the Apr 2025, if I understand correctly. However, at that time, I will not be in UK, so it may not be easy for me to send the huge money online. Using the 20% tax rate, the tax I should pay is more than 30K pounds. This is not small amount of money for me, so I would like to avoid sending them internationally in the future. If possible, I would like to pay the related tax in advance before I am leaving UK. Could someone give me an advice?

Hi,
You can use the calculator at Tax when you sell shares to help you work out your gain.  
If you have or are able to obtain a government gateway user ID and password, you can report and pay the capital gains tax using the realtime capital gains
tax service at Report and pay your Capital Gains Tax before 31 December 2025.  
After this date a self assesment tax return is required.  
If you complete a self assessment tax returns, you could send the payment to your self assessment record.  
It would sit there in credit until 31 January 2026, when the capital gains tax would become payable.  
Thank you.