I am a UK resident who's Thai girlfriend is due to give birth to our first child shortly. After registering the birth at the amphur & getting a Thai birth certificate I was thinking of heading to Bangkok to sort out a Consular Birth Certificate. Looking at the UK embassy website it states that I need to get certified translations of any non-English documents. I know translations are fairly easy to come by but can these be certified by the translation company themselves or do I need to get them certified at the Ministry of Foreign Affairs ?

Ask the embassy, but normally these kind of documents need to be legalised by the Thai Foreign Ministry.

Note that as you are not married, under Thai law you will not be the father of the child in a legal sense till you petition the court to be recognised as the legal father.

See: http://www.thaivisa.com/forum/topic/381917-how-to-gain-parental-rights-as-a-father/

Got a reply from the Consular section of the UK Embassy that says a visit to MOFA is not required.

As we are unmarried I asked them about the need for a paternity declaration to be completed based on the following information from their website :-

"If you are a British man and your child's mother is foreign you can only apply for a consular birth registration of a child who was born on or after 1 July 2006. If you are an unmarried woman who's had a child abroad and you would like the father's details recorded on the document both you and the father will need to swear statutory paternity declarations in front of a UK solicitor/commissioner for oaths. This is sworn in front of a consular officer if you are resident overseas".

They have said we don't have to complete paternity declarations which surprised me. The only reason I can think why we don't is that the bit I've highlighted in bold only applies to unmarried UK women who have a child abroad, does anyone know if this is the case ?

Seems only the top of the statement, which you dind't highlight, regards to you. With unmarried woman they might mean unmarried British woman.

Do recognise the child under Thai law, without that you will not be considered the father in a legal sense and can also not get extensions of stay based on the child from immigration.