My favorite tactic for this fight is Aard, fast attack to close the gap, strong attack to hit him hard, rinse and repeat. If you hit him with Aard before he can cast Quen at the beginning of the fight, you start with a big advantage.
If he blocks you, roll away before he hits. If he throws bombs, roll and run away from them. If you get hit with a critical effect (bleeding from his sword, poison or fire from bombs), cast Quen immediately to stop it.
If he casts his Quen shield, cast Yrden to immobilize him. While waiting for his Quen to come off, get behind him, then stab him in the back. This is not Marquess of Queensberry rules. This is do unto others before they do you.
If you need somebody to play this through, you can use any service that allows you to upload and download large files.
I favor
Dropbox.