you can claim (anyone can claim)
you will be rejected (you have left it to late)
you will then have the right to appeal (and provide evidence as to why you didn't claim on time and why you have grounds to have a rejection overturned)


i can suggest there would need to be a better reason that forgetting - that one won't cut it sorry! i don't think there would be too many reasons that would be accepted (perhaps illness preventing you from claiming - with significant medical documentation to show that it was impossible)

i really think you've missed your window of opportunity on this one