Re. Replacement glass panel for Canon Coalridge Balanced Flue gas fire?

Hi.

I have a Canon Coalridge Balanced Flue gas fire where the front glass panel has a crack in it. Been on various websites and they're asking a fortune for a complete replacement.

I'm sure I could get a replacement piece cut to size alot cheaper. My question would it be would it be safe enough doing it this way and what specification do I need to ask for? I would obviously have it fitted by a gas safety registered engineer.

Thanks in advance for any advice offered