Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
You should be able to find your UTR on any items sent to you by HMRC like letters or notice of tax codings etc. It may even be on your P45.
I do hope that you have found my reply of assistance. Just Answer is an independent tax advice site and not connected in any way with HMRC.
I am on 01750 725420
The UTR is a five digit number followed by another five digit number eg NNNNN NNNNN. The UTR is often the tax payer's tax reference number also. Certainly it is for me.
A new employer does not need an UTR, the P45 has sufficient data for their tax office to pick up the account. If there is insufficient information the new employer will issue a Form P46 to their tax office which will enable them to pick up the account.
Thank you for you support.