The amount you will get paid depends on the amount earned and your tax code issued by HMRC.
An example is If you work 20 days a month at £100 a day and are part of the Teachers pension scheme you are likely to get paid
£2000.00
Lees NI 165.60
Less Pension contribution 220.00
Less Tax (assumimg you have standard tax allowance etc) 139.54
Take home before other deductions e.g. student loans £1474.86