SMP and SSP advice please?

i have two weeks left at work wel.. i am working til the 4th of Aug then i have holidays in from 5th 6th an 7th Aug then i am to start maternity on th 10th Aug but i am Absolutely full of cold and really down and tired i cnt sleep on a nite and im up tossing and turing alll nite long then i have to do a full week of 37 hours a week.. my body is drained am on iron tablets but they dont seem to work.. iv requested to go on maternity leave earlier but work want 28 days in writing which is pointless because i am leaving in 2 weeks. if i went on sick with a doctors sick note for 2 weeks would i then still receive my 90% of wages after this and then the rest of my maternity pay?..