I just know you're going to growl at me for saying this...but - YOU are responsible for keeping track of the dates etc. (You are a responsible person, are you not?).
Anyway - the good news. Fill in
http://www.caa.co.uk/docs/33/FORSRG1106.PDF and send to the address that they have printed on it.
Attach a covering letter asking for a new brown folder for your PPL.
Don't send any money - for either the FRTOL or the new brown folder. They are both free.
Now....smile!!