Sorry to disappoint you but to get a seat in government medical college in Tamil Nadu you need to score more than 600 under All India seat and 550+ to get admission under state quota. Though you might get a seat in some low ranked private medical colleges but getting mbbs would still be difficult. 

You can check previous year's cutoffs of colleges in Tamil Nadu by going through this link.

https://medicine.careers360.com/articles/neet-cutoff-tamil-nadu

You can predict what colleges you might get with these marks by going through the link of neet College predictor tool given below.

Https://medicine.careers360.com/neet-college-predictor

Hope it helps.

Thank you