Assuming your daughter has her self-assessment tax reference number (ten digits) she should register to complete her self-assessment tax return online here
. HMRC are unlikely to accept a paper tax return at this late stage. She will have to wait for an activation code to arrive in the post before she can complete the tax return online. She really needs to get it submitted by 31 July to avoid a further penalty for late submission. The penalty for missing the 31 January 2013 deadline is £100 and daily penalties have been running at £10 per day since 1 May 2013 There is some information on the penalties for late tax returns and late payment of tax here
Your daughter can complete the pages she needs by hand by downloading them from here
. She needs the 2012 SA100, the employment pages SA102 and the self employment pages SA103S or SA103F. She can then copy the figures across into the online form when she has received the activation code.
Your daughter's income in 2011/12 was £17,226. The first £7,475 of her income will be tax free so that leaves £9,751 taxable at 20% (£1,950.20). Class 4 NIC at 9% is payable on the profit between £7,225 and £11,489 (£383.76). So, the total liability for 2011/12 will be £2,333.76 less the £324 tax paid so the net liability is £2,009.76. That's assuming she has no expenses to claim against her income from self-employment. Take a look here
for information on expenses which can be claimed.
I hope this helps but let me know if you have any further questions.