As @scottbb mentioned The Lee gels are meant to filter the light source. Usually for mixing fluorescent lights with other sources. You can put them on the camera, but it will be optically worse and won't do anything you can't accomplish in post.
Since you are shooting digitally – you mentioned MFT – you are better off doing overall color balancing in the computer.
Also worth noting: modern fluorescents can be many different colors, not just the green the Lee filters are compensating for.
Using a color standard like @Tetsujin suggested is a good idea, but don't try to match it so closely that the image looks flat. Every client I've worked with preferred a good looking photograph to an accurate one even for reproduction work.