Unless your brother is very dishonest, it will not 'automatically be distributed' amongst the three of you. Somebody has to do it, and they need legal authority to do it.
Unless it's a very small estate, Letters of Administration will be needed, and unless your brother denies your existence to the solicitor and the Probate Office, they are likely to insist that at least one other person is named as Administrator.
So apart from arguments with your brother you've nothing to worry about.