You can contest a Will after probate has been granted. The problem with this is that the assets of the estate may already have been distributed, which can make it more difficult to get back what you are entitled to. It is therefore strongly advised to seek legal advice as soon as you believe that you may have a claim. We can put a Caveat on the estate which would prevent probate from being granted while your dispute is being dealt with.
There are strict time limits for contesting a Will and these depend on the type of claim you have. You can read more about the time limits here.