Returning from Mat Leave

[KLAND]

I am due to return to my job after having a year off on mat leave in January.
I have mentioned to my boss when I visited her that on my return I would like to work full time (35hrs), but over 4 days due to childcare etc rather than 5.
She has expressed how 'It is really a full time role' and basically expressed that she is not willing for me to return 4 days a week.
I have 2 children 1 is 4 and 1 will be 1 on my return and am a single parent.
Can anyone suggest how I go about getting my boss to agree with my request?

[THECORBYLOON]

The link here, http://www.dti.gov.uk/files/file21364.pdf
is a Department for Trade and Industry (DTI) leaflet about appying for flexible working, yir rights, how to do it and the acceptable areasons for refusal.