Hi,
If you meet the Self Assessment criteria for 2023 to 2024 then depending on the reason why you need to file the Self Assessment you can file the tax return online. You can see guidance here:
File your Self Assessment tax return online
On your personal tax account (PTA), if you select the Self Assessment tab this will allow you to enrol to file online. Once enrolled an activation code will be sent to you by post. Once received you can log in to file the tax return. To view your PAYE income you select the PAYE tab on your PTA.
Thank you.