Please refer to the following link for a detailed guide on reaching Kodaikanal from Bangalore: https://www.holidify.com/places/kodaikanal/how-to-reach/bangalore-to-kodaikanal-920.html
Bangalore - Salem - Dindigul - Kodai Road - Kodaikanal route is pretty good, except for a few rough patches here and there. You can go for it. It will take you about 7.5-8 hours