I need to replace my door mirror glass, any tips.

Seems very tight to remove.

Done this a couple of weeks ago.

Followed some instructions I found on the site somewhere:

Adjust the mirror so it is pointing towards the car, this will give you some access space between the glass and the edge of the wing mirror housing. Using a big screwdriver (or in hindsight a spanner as you want a wide area to lever on), lever the glass out. It will pop off out of the housing. If they are heated then the wires will stop the mirror from falling completely out and crashing to the ground.

I ended up reusing the original SKODA black plastic back plate as it was much larger than the one that came with the replacement - more surface area for the glue to stick onto.

Just don't press the replacement glass in too hard as you don't want to crack that nice new mirror glass. PRACTICE PUTTING THE OLD ONE BACK IN FIRST!

Or alternatively, I just stuck the new glass over the top of the old cracked glass, so it is now double thickness. Heater still works just as well, with no visual difference between sides.