Is a CT scan finding of 'fat containing inguinal hernias, left greater than right' significant? My gp didn't mention it.

Fat. Findings of fat on a ct scan may be a normal finding of a fatty "cord lipoma" that needs no treatment and is observed. Ct is not good for hernias unless they are larger. Need to have a corroborating physical examination to see if the ct scan findings are causing an internal lump or swelling at the site where hernias occur.
Incidental. Seen so commonly on ct scans of the abdomen that many radiologists won't mention it. If your referring physician didn't mention it i wouldn't worry about it.
Depends on. Whether you are having symptoms. If you do have any pain or noticeable bulge that is disfiguring, you need to have surgical repair now, and you might never need it. That is probably why your gp did not mention it to you.