system
Given the following post, respond as if you're commenting on Reddit:
human
[Warhammer 40k] Can you have void shields open at the same time as gellar fields? (and other questions about gellar shields.)

Or are the two shields mutually exclusive?

Can you have void shields up when in the warp? Or is that impossible/meaningless since they rely on the warp to function?

Is ship to ship combat using regular weapons possible when travelling in the warp? Or does that require you to move so close to a enemy vessel that your gellar bubbles merge?

And finally, how well, if at all, does gellar fields protect you against weapon fire?
gpt
All the gellar field does is close in "reality" around your ship keeping the warp out. This means daemons cant make your ensign explode in a ball of puss and flies. 

It has no effect on ordinance, you can and should run both shields at the same time.