"I would like to not have to do either and somehow splice the wiring
together in the
attic area rather than having to fish wires through the receptacle or
switch wall. Any advice would be great. "

The other alternative is to use two junction boxes in the attic. Cut
the cable going to the outlet and put one end in each box. Then run
your new light cable into one box and run a short piece of cable
between the two boxes.