You do not need to be classed as an employee to get Statutory Maternity Pay (SMP) although unhelpfully, only employees are entitled to take maternity leave. You will be entitled to SMP from your agency if they deduct tax and National Insurance from your pay, through PAYE and you qualify under the following rules:
Even if you have not worked for the agency in each of the 26 weeks ending with the qualifying week, you may still be entitled to SMP if the reason that you did not work is one of a number of permitted reasons. These include the fact that the agency did not have any work to offer you or the fact that you were unable to work due to sickness, or were on paid annual leave during that week. If in doubt about your entitlement, seek advice from an advice agency.
If you qualify for SMP, you will receive maternity pay for 39 weeks and this will be paid at 90% of your average pay for the first 6 weeks and then at a flat rate for the remaining 33 weeks. From April 2009, the flat rate is £123.06 per week.
If you do not qualify for SMP, you may be able to claim Maternity Allowance from your local Benefit Agency office and you should contact them for further details and an application form.