I agree with lonemagpie's suggestion, Backwards, for the same reasons. He's seen The End, so he knows the setup, and Backwards is a mini reboot.
I don't know that "Backwards" is really a mini-reboot. Yes, it's the 1st episode to feature the new Series III-V look. But it's not like it does anything special to really ease you into the characters or the new situation. That super fast, unreadable opening crawl could have just as easily been tacked onto the beginning of any of the Series III episodes.
Series VI does a much better job of beginning with a mini-reboot in "Psirens" with Kryten gradually bringing Lister & all of the other characters out of stasis one by one.
Right now, this is the order that I'm contemplating:
1. "Meltdown."
2. "White Hole."
3. "Polymorph."
4. "Backwards."
5. "Quarantine."
6. "Holoship."