Drape your goods in the attic.

I'm not expecting any wood to need to be replaced, but I might be unpleasantly surprised.

Yep, sure as shootin. You better be prepared to fix any bad roof
decking, if the roofers aren't required to do those fixings. There is
usually always something that needs fixing, especially old T&G
decking. Some worker just may step on a weak board, or boards, and
punch through. Also, have some 2X4s or 2X6s and nails handy, to
sister along any roof rafters, for conveniently replacing any
decking. Be prepared to fix anything as that. If there ends up to be
nothing to fix, I wouldn't think you would have invested too much
expense for the preparedness. You don't have to replace/repair the
decking with T&G, plywood is fine.

Check from the attic side to see if you can spot any rotting or water
leak areas, especially around any vents, chimney, etc. When the
roofing material is off, go stomp on any questionable/suspicious areas
and repair, if needed.

Sonny