Thanks for the replies, very helpful.
So my understanding is that the birth itself will be quite expensive, but will be covered by her work health insurance (she can check the criteria for this with her company). Failing that, the govt 30 baht scheme will cover her if we use a govt hospital which is part of the scheme (which I hear are pretty good anyway). Then optional extras can be added and paid for as we go such as private rooms etc.. Even the prenatal check ups should be covered by this, although that's not such a problem, it's the birth cost itself I'm concerned about as it's quite a chunk of money.
This seems to make sense, I hope it's correct, please correct me if I'm wrong.
As for the govt 30 baht scheme, it seems from my research that any Thai citizen can use this in any approved hospital without prior arrangement, you just need to make sure that the hospital you are using is approved by the scheme and show your Thai ID card when you arrive to receive free treatment? It seems you don't need to pay in to National Insurance or anything like that as it is covered by standard taxation and available to all citizens regardless if they are employed or not. Anyone got experience with this? As I said, the GF is clueless and my concern is getting a massive bill after the birth because we didn't register or fill out a form or something, or because she hasn't paid in to the scheme.
If anyone out there has recent experience with this and can clarify the above details this would be a great help. Hopefully this is helpful to anyone else in this situation too.
Thanks so much guys.