No issue with him taking a family holiday in half term at all. Why would I? I have no issue with anyone taking time off and having a holiday with their family regardless of their income or occupation.
And it is only Ibiza. He is not at the other side of the world or in the middle of nowhere with no form of communication.
I suspect like many other working people on holiday, especially those with higher levels of responsibility, he will be checking in regularly, responding to phone calls and emails, etc and being kept in the loop. If there was a huge emergency he is close enough to be back in the Uk within a few hours.
TBh when you have a job like PM there is probably no ideal time to be away is there? There will always be something, somewhere, he could be attending.
As for those who think that the PM shouldn't be going on any abroad holidays, or even any holidays at all, because he should think of those who can't afford it - really? You think ANY politician of ANY party would be doing that? Really?