check the timing in following web site to know current status of booking and train available and ect.
www.IRCTC.co.in
From Main City to Coimbatore you have 24 hours Bus services available from Government service, Also for Special Bus like Sleeper Seater and semi Sleeper Bus also Available for night Traveling. In Coimbatore There are lot of Private Bus service also available and Transportation you have private Travelines also available.