even if non-dom in UK, if it's UK sourced income you'd still have to pay tax on it in the UK. It's foreign income you can elect not to pay tax on in the UK as a non-dom UK tax resident provided that you don't remit the income to the UK. I appreciate that's an incredibly simplified explanation above but that's the general gist of it.
Doesn't work like that I'm afraid. Tax is paid where your income is earned. In order for it to be taxable in Thailand you would need to remit your income to Thailand BUT doing this doesn't necessarily mean Thailand will have primary taxing rights.
The above does not take into account you are on a tourist visa, which may null and void the above anyway.
we'll have to wait and see but I very much doubt it will be only for 2 weeks considering it will take nearly 2 weeks to get a better idea as to how much Songkran caused it to spread.