To be honest with you, you don't need to have a lawyer to do so. However, you may need to make sure that you are understanding the procedure and you could actually communicate with the land officer and/or your assistance in this regard. This is because all legal documents are only in Thai languages. You may need to have a lawyer to explain all procedures and provide you with the acknowledgement of the transaction of buy & sell, accordingly.
When buying a Condo here in Thailand is it necessary to employ a Lawyer & if so how much should this cost?