It seems to me, to build a Tamil spelling checker or NLP with AI/Machine Learning one may start by reading this works,
1. http://www.diva-portal.org/smash/get/diva2:1232482/FULLTEXT01.pdf … word representations for LSTM NN
2. Automatic Spelling Correction for Resource-Scarce Languages using Deep Learning
3. Attention-based encoder-decoder networks for spelling and grammatical error correction
