Funny, I was in the same situation recently & was assured by several clubs I spoke to that it was the flying rather than the paperwork that had to be done before the expiry date...
They said that if you sent the documents with a covering letter to the CAA with an explanation of the reason for the delay (out of country, sick, pressure of work etc etc) they are known to give you a dispensation.
Any ideas what the truth is??
PS. As it happened, I ended up 1.5 hours short on the solo

....& so spent some time with Mr Examiner