Will my expired passport affect my ilr??? Help needed please

[Darkangel]

Hiya everyone,
I need your help please..my passport expired in March and I am applying for ilr(set)M at the end of this month..
I'm wondering,does it matter if the passport is expired or not,or do I have to renew it before applying?
I have an appointment to renew it but I'm thinking of cancelling cos I can't be able to take my English exam which comes up after the passport renewal appointment(Nigerian embassy takes away your old passport and I need it for the exam) any help is highly appreciated..thanks.