How to provide power to laptop in unused ceiling access panel?
Besides having chosen possibly the most hostile environment to run a laptop, you have an advantage in using a laptop...it probably has a wall wart transformer and some lower voltage lead that actually goes to the laptop.  Since this is low voltage wiring it is much easier to run and not (usually) restricted by code.

So, the right thing to do, if you insist on the location, is to plug the transformer into some outlet relatively nearby and run the low voltage wiring from there to the laptop.  This may require splicing in additional length, or even getting a replacement connector to terminate on.