Wiring advise for bathroom fixtures

Hi all, Need some advise on how to proceed with this if anyone out there has experienced doing this. Just moved into a new ( older) house and in the bathroom there is a medicine cabinet/mirror. Instead of a wall switch there are two small incandescent fixtures on each side of the cabinet. At the bottom of each fixture is a plugs and a small rotary switch that turns each one on individually. I would like to add a wall switch and plug next to the right hand fixture about a foot away. Then add either a light bar above the mirror ( would require patching ugghh) or two small fixtures to replace the existing so no patching. I am guessing that the easiest thing to do is remove the medicine cabinet and then try and fish wires to a new box cut in on right side. Both fixtures should have straight power all the time now so I can do any additional splicing in the existing boxes. I am wondering if there is usually room between the back of cabinet and wall to run a new line behind it if need be. Thx for any assistance.