Not that it stopped me before, but I have no experience in this. My first guess would be that you need to find the last armiger, then trace a direct line between him and yourself. That line would probably be subject to primogeniture, i.e., you would only be able to inherit and claim if no one with a superior claim is alive. I would next imagine that you will have to submit your pedigree for verification and inspection by some approved genealogist, though the Lord Lyon may take care of this.

If by happy chance, you are the eldest son of the eldest son, etc., and you can readily document this, it might not be too difficult.

Surely Rathdown can help us here.

Good luck