Tax question

Will you be working for two different companies?
Do they pay your tax (PAYE)?
If so then they will sort the tax out.

We receive pensions from more than one source and HMRC know this and show you the tax coding applied to each payment on your annual Tax code statement. It does work similarly if you are working as you only get the one total Personal allowance -about 11K I think it is now.

No, I'm planning on just working for company I'm with now, with proper contracted hours. I didn't resign from my zero hours job, as I wanted to keep my options open for a bit!

In the old job, were you classed as self-employed for tax purposes, or on PAYE? If the former, you'll still need to complete a self-assessment tax return for this tax year. If it was PAYE with tax deducted at source, HMRC should work it all out and apply your personal allowances to the total, although it may be months until it catches up.

It was PAYE grannyticktock.
In my long winded way, I wondered how to make my new job my main one, as I dont want to pay huge amounts of tax on it. I suppose it will get sorted out, eventually though?

Whatever happens, check your P60(s) at the end of the tax year to make sure they got it right.

I think you would need to get a P45 from your old job, in order for your new job to set themselves up as your main employer.

The tax you pay will be the same which ever job you say is your main job. HMRC are interested and will tax you on your total income, regardless how many jobs you have

It is good practice to tell HMRC about both your jobs. If you do not tell them yourself. They will find out when your second employer makes their annual return of employers earnings and tax, so you would be chased for tax due a few years later.

More to the point, your permanent employer may put you on emergency coding until they get a tax code or letter of exemption from HMRC so you will be paying more tax until the problem is resolved.