If the last game "your grandfather" was at was the cup game against Celtic then he can't be as die hard as you say and won't mind watching the game at the pub.
Let's face it, your not gona get a ticket on here. God loves a trier and 10/10 for effort but there is absolutely fuck all chance that anybody on here is buying this. The only chance you have of a ticket is a scalper, of which there are always plenty of at Rangers games, and probably for the end you are actually wanting to sit in.