Julianna Hambright

Please can anyone help with this question. My brother has recently passed and he left a basic will, he was an army reservist at the time. His ex-wife was named on the, and I have been reading that this will is now void, is that right. I'm my brothers sister and I will be applying for probate. Do I apply for the PAP1, as there is a will but it hasn't been updated. Or do I apply for the PA12, to administer the estate. Any advice would be much appreciate - thank you!