Is there anywhere to rest in the lair? I sorta got stuck way back in it and I'm now having to try to kill everything on my way to the door. Low on healing potions, low on spells.

What level in Dragon's Eye are you on?

I'm in Chult, the "Lair" under the platform where I will have to fight the guardian. I have a reload available before I turned the lair against me, but I want to play through if I can.

If you are by the alter/high priestess chamber, you can rest in her chambers (after killing her ;) ) if you close the door.

GREAT!

Follow-up: too busy tonight. Will aim to check out Pinky & the Brain's advice manana

You can rest in either room if you made sure you cleared it first of course. There always a possibility that one or two Yawn-ti's ( :D ) spawn when you rest, but that shouldn't be a real problem.