How long do I get to pay once I declare?

Hello. I have completed my self-assessment until the "submit" part, and the calculator says I own around £6,500. Before I hit submit, I want to know how long I will have to pay it. I don't have the full £6,500 at the minute. I am a couple of months short. If I submit it, will I have a few months to pay or am I given a short deadline? I am aware I don't have to submit it until January when I will have the money, but my mortgage deal needs renewing, and I will need the figures to apply for a better deal. Also, are monthly payment plans still available? A couple of years back I owed about £3,000 and was offered to pay c.£250 a month for a year or so (I can't remember exact figures/duration).

Can anyone help?

Hi lee Stafford,
If the amount is from your 22/23 tax return, you would have until 31/01/2024 to pay this regardless of when you submit the return.
Unless you already have Payments on Account previously generated.
If you are unable to pay in full by the deadline please see:
If you cannot pay your tax bill on time

Thank you.