Am I correct in thinking that when I arrive and go to stay at my GF house I should indicate this on my arrival card (or will the area suffice) and she has to notify Imm of my stay. Is this a one off at the address - only to change if we change address?

Do I also have to notify Imm of the address at which im staying? and again this will suffice until we move house?

When we build or purchase do we have to do the same thing again?

Put your address on your arrival card. Up to girl if she wants to report - most will not bother. If you start staying more than 90 days in Thailand you will have to report your address to immigration every 90 days.

Thanks Lopburi3