Worried about deadline

So I've filled in the online part of the application but I still need to send in a birth certificate and the deceleration form. Do they need to receive these before the deadline? I can fill in the deceleration form and send it off tomorrow, but at the moment I can't think of anyone to sign the birth certificate form for me, so that might cause a further delay. I'm just hoping the fact I've submitted the first part of the application counts as meeting the deadline. If not am I screwed? :/