Upnotover

https://visa.vfsglobal.com/tha/en/gbr/hmpo

I buy them from Villa. Aussie style, made in Phuket. Good enough for me once a week or so

.

SRT Long Distance Train

One way. No problem.

It's worth noting that currently showing up to 3 April. So it will be 4 more days until new appointment dates appear, (4 & 5 April being weekend, 6 is a holiday). However, it never hurts to check daily as cancellations can occur randomly at any time.

I always go online at 1am. I never had any problem getting an appointment.

https://bangkok.immigration.go.th/wp-content/uploads/APPLICATION-FOR-A-LETTER-OF-RESIDENCE-INFORMATION-IN-THAILAND.pdf

I think you may get a 30% refund. But it would be far better to ask SRT for confirmation.

And if you were, apart from how you would get there (maybe hitch on Anutin's rescue flight?), what business is it of of theirs?

Did you already look here......https://th.usembassy.gov/getting-married-in-thailand/

Mine are, to Kasikorn, and are identified as such on the printed statement.

What did you provide to show your physical presence in Laos? Entry stamp/visa?

Agreed. But in actual fact the London Embassy did exactly that a couple of years ago with my non-O application.... "Other request documents: - Flight details showing the applicant’s name, departure date, all flights en route from UK/Ireland/UK territories to Thailand" It was no problem for me as I had a ticket and I don't ever remember seeing anyone else reporting the same issue. But in the OP's case I am certain there would be no problem.

Yes, take old and new passports to the bank and they'll update. This should be done irrespective of whether you need something for immigration.