I still don't understand how anything mentioned is at all relevant.
The UK has many tax treaty's with USA (largely complicated), Singapore, India, Australia, Pakistan etc.
Eg
"Claiming Double Taxation Relief for companies and other concerns".
I simply don't see how OP's situation is relevant to @Festivecheer26 's statement : "company may suffer tax consequences under the relevant tax treaty". What tax consequences might OP's company suffer? For her 1 month?
I still don't see how any of the OP's situation is at all relevant.
How would OP's situation affect corporation tax? The answer is, it wouldn't.
A company may need tax advice if a number of their employees are travelling or working abroad for a period of time.
It doesn't apply for most normal people going for a weeks holiday to Benidorm/Malaga and needing to respond to an email.
Spanish
The Spanish Tax treaty is in respect of residency. Living in the UK or Spain for "183 days per year".
Which is exactly what I claimed right at the start. I asked anyone to link anything that had more info than the HMRC re working abroad, or residency. It needs to be for a large proportion of the tax year.
OP's 1 month does NOT count.
Even @Howmuchwood said in her second point : "1 month often fine".
So none of anything mentioned applies.
Clearly I've over invested in this thread. But I hate it, it gets my goat, when people come on sprouting false and factually incorrect technical and legal terms.
Many posters posted about tax implications. But it's nonsense. It doesn't apply to OP's situation.
Why can't I do this boss? Um, um you can't. Why? I don't know. Er maybe there are ...,. Tax implications.....
(Er. No. There aren't. They don't apply)