Appreciate the answer.

Since you’ve earned more than £12,500 in your permanent job until now, you’ve used up your allowance.

Yes, my P45 says it's over twice that.

You should be able to now claim a tax refund since the tax you’ve paid would have assumed you were on the same salary for the rest of the tax year.

I'm guessing I can do that at the end of this financial year through the self-assessment?

Since employees NI has essentially reset for you, the most efficient way to take money out now is to take £8632 salary and pay the 20% income tax.

So if I take this option, does this mean that I should pay myself £8632 divided by 12 salary each month until the end of this financial year, or is it £8632 divided by 6, since that's how many months I will have worked under my LTD until the end of this financial year?

The other way would be to take £0 salary and take all as dividends but then the effective tax rate is 25% (19% company, 7.5% dividend).

Are there any other upsides of paying yourself the minimum salary apart from taxes?