work from home tax expenses

fartington

my wife has got all the kids in school now and wants to start some work again. She has just got a PA job part-time job, self-employed from home. She will be working 4 hours a day and earning approx £900 per month but it will vary as she might have some bonuses but equally hols and off sick, she will not be paid, so we estimate an annual income of £9500-11000. It is may or may not be over the tax threshold, and we will only know at the end of the year. Also there is national insurance payment, which is 9% over approx 7500 profit.

She is training this month and will get a small training payment and starts being paid properly in march.

1/ when does she register as self-employed?
2/does she register for NI as well right away?
3/does she pay NI right away?
4/when do we fill tax return.
5/when do we pay NI balance.
6/can she claim council tax, power,heating, internet and if so, in which percentage? anything else she can claim? she does not use the phone or miles etc. How much is realistic for a PA to claim, as i do not want her to under-claim, if she is entitled. I was thinking around £500 max after totting up. It may reduce her profit and therefore the amount she has to pay for NI.