does anyone has a simple rental agreement in English ? need a copy

It's unlikely you will get one due to competitors, you are better off googleing "Lease Agreement Example"

Three Property

All of the ones that I have found have been pretty bad, and they are not worth the paper that they are written on in a court of law.

I once downloaded one from the internet and modified it to fit the situatiion. There are many aviable to download free.

If there is a dispute later, will the english lease be valid in Thailand?

All of the ones that I have found have been pretty bad, and they are not worth the paper that they are written on in a court of law.

pm me and I will give you one I have used for many years successfully

If there is a dispute later, will the english lease be valid in Thailand?

All of the ones that I have found have been pretty bad, and they are not worth the paper that they are written on in a court of law.

No

Any good landlord or agent will have the contract written in Thai first with English translation, not vice versa.

Three Property