Hi Rachael,
Whilst I don't suffer from CB, from my own personal experience, you usually get the review form approx. 6 months before your current claim ends, but still have roughly a month to fill it in - however due to the postal delays, if you need more time, you can call the PIP enquiry line, and they should issue you a further 2 weeks, and send out another form. Unfortunately, I believe the form has to be filled in again in the style of a new claim, so you will have to answer every question as such, and submit any evidence you wish too.
Regards, Chris.
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
