Koh Thai Tapas has many locations across the South West. The one I visited is in Bournemouth's town center.
Koh Thai is very different during the day and during the evening. The only constant factor is the great food.
If you're looking for a quiet, family friendly restaurant to eat some good Thai food then visit Koh Thai during the day (they also have a special set menu for just £12). On the other hand if you're looking for a dark restaurant, filled with young people, music, great cocktails and food then you must go during the evening, especially on Friday or Saturday.
I highly recommend the Penang Curry with coconut rice.