As Mike says - yes you can rent a car in Thailand without the correct licence.Just come and enjoy yourself and dont worry about such a small issue as a license
Good stuff - you've saved yourself a few measly pounds.........
Now - you have an accident and seriously injure yourself or someone else.

1. You are driving illegally so your medical / travel insurance can choose not to help

2. You are driving illegally - we all know what the Thai authorities make of that.

3. Any driving insurance that you take out may be invalidated.

Come on.

If you come from the UK refer to http://www.theaa.com/getaway/idp/motidp005.html
Peter