Memories of a holiday is correct English and would mean memories from a particular holiday / vacation. A holiday (excepting in the USA) means a trip for pleasure. Memories of holidays (again, except in the US) would rather mean a collection of memories from different holidays you have been on.
"memories of holiday".. being accepted as well, is this idiomatic? I'm not a native speaker obviously, but it doesn't even look grammatical. I answered "memories of a holiday" only to be told I'm wrong. Tell me I am, but to me it looks like a perfect phrase, even a sentence, almost "English". So if this is not a correct translation, how would my answer be translated into Polish?
Ah, it seems you'd have to use another word if referring to a single day like I did, like święto. But that would probably only work as long as we're talking about an official day of festivity, that's what in German we call a "Feiertag", but not if it's just a day off school/work.
Even though "holiday" comes from "holy day," it is the British English word for vacation, but in American English, a holiday is Christmas, Thanksgiving, Easter, New Year's Day, etc. How would you say "holiday memories" in this regard in Polish? In Russian, the British English holiday would be otpusk, and the American English holiday would be prazdnik.
Well, "a holy day" is actually visible in Polish, it's "święto" (święty = saint, holy).
Now, "holiday memories"... technically "świąteczne wspomnienia" or "wspomnienia ze świąt (plural) / święta (singular)", but only the first option sounds natural to me. Moreover, I'd automatically assume that it's about Christmas. Maaaaybe Easter, if the context made it most probable... but almost surely Christmas. If it wasn't Christmas, I would specify the holiday.
Well, with vacations, it seems logical to use "z" because they are memories from the time when you were on vacations. I don't think I'd use "wspomnienia wakacji" although I'm not sure if I'd say that's totally wrong.
"Wspomnienie wakacji", with singular 'memory' makes more sense to me, actually. One memory, one reminiscence of the vacations...
"mego" is perfectly fine, it's actually more poetic. So it's used more in poetry and songs, not only good songs, of course. It's rather not accepted in this course because not many people even think about putting it and let's say it's non-neutral.
And I totally agree with both va-diim's comments. The song clearly was about just one story and not the whole singer's life.