Hello every body, I am a British passport holder married in Thailand and entered Thailand without a visa, I was given the usual 30 day on arrival visa, I now want to extend that visa at Soi Suan Plu for an extra 30 days, I know I can get this extension being married but at the end of that period I would like to go make a visa run to the most convenient border and obtain another 30 day extension.

Is this possible and which border is the best, I am thinking of going to Cambodia

You can not extend for 30 days at Immigration. You may be able to use the one time 60 day extension of stay to visit wife under section 7.23 of Police Orcer 606/2006 using below documents:

1. Application form

2. Copy of the applicant's passport

3. Copy of household registration

certificate

4. Copy of the national ID card

held by the Thai concerned

5. Copy of the marriage/birth

certificate

For future you need to do some planning as to how long you plan to stay etc

Cambodia is best used when you have a ticket out within 30 days that you can show. Plus visa exempt entry is limited to 90 days in a six month period regardless of marriage.