Hi,
Try in 17643 circar express. Departs Chennai Egmore at 17:20 on 12th and arrives Rajamundry at 08:05 the next day on 13th. In 3A there is availability.You will easily get buses from rajamundry to Tuni. All vizag buses from Rajamundry go via Tuni.
Otherwise if you wish to travel in a superfast, try 12842 coramandal express on 13th that too in sleeper class. Departs Chennai central at 08:45 on 13th and arrives Rajamundry the same day at 17:32. Sleeper class tickets are available on 13th from chennai central to rajamundry.
Plan...
more... quickly and book your tickets as soon as possible mostly today itself.