In general, you must begin your personal injury claim within 3 years of the date of the accident.
If too much time has passed since the accident in question, you might be prevented from making a claim. See our Knowledge Centre entry on limitation periods.
There are a number of rules which can change the time limits which apply to your case. If you are thinking of bringing a head injury claim, or you are worried matters have been left for too long, contact us as soon as possible so that we can advise you on where you stand. Limitation law is called complicated.