Dear Mike ...
You are building next to the Outlaws ... have you ever lived with them for months on end?
Assuming not ... not a good idea to build.
What works in England (housing design) doesn't translate to a hot humid climate of Thailand.
'a four bed two storey house' ... do you have lot's of children? I'll assume not. Crazy to build anything of that scale.
You won't be there for the build ... disaster awaits you.
I'm just waiting for the statement ... Nah, it will be OK, my MiL and FiL will supervise the Build ...
Thais traditionally build on a 4 x 4 metre platform and varying that (building to an English plan) does throw up some issues and potentially extra costs.
That said ... all good fun, good luck with the build.