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Thanks everybody for all the very useful information which I have relayed to her. She did plough through the you.gov link and of course now, we are in a new tax year, answer is as was stated, they send a P800 between june and september.
I also got her to set up an online HMRC account, of course myself and my husband have one due to our having to complete tax returns, but didn't think of her having one, as with PAYE isnt really necessary. It's a good while since we had to have anything to do with HMRC so it didn't cross my horizon.
I knew I'd get good answers on here, I've never been failed yet, so thanks again.
However, she has done this, and it's very useful, it does give her all the necessary information she needs, and the live chat, when it is live is probably better than trying to ring them.