cluttered, DD1 is in Yr11 this year.
I started a thread about whether skiing in February half term would be okay, last year, and the general consensus was that February is fine, but Easter could be problematic.
Now we are in the midst of revision. We did go away in February. And she took books with her, but TBH, I don't think she did all that much work.
But this Easter, she has done loads, even staying at home when the rest of us have gone out for day trips. (Although balletmum will be pleased to note she did come to the theatre with us on Saturday, and a nice long walk, Easter egg hunt, etc, yesterday.)
There is always revision to be done, but I don't think it really ramps up until now.
But, OP, I really think May is just a no-no. Seriously, these GCSEs do take over your life (and I'm sure A levels will, too). But, it's part of what you take on as a parent, really.