The non-Schengen lounge at BCN is pretty basic. Not that much different than the Schengen or MAD-shuttle lounge honestly.
Food choices are pretty basic (hand sandwiches with a little meat, mini muffins, little pastries). Basically not "real food." They do have an ok selection of soft drinks, beer, juices and coffee though. I don't recall ever seeing salad there, but I usually fly early morning. Maybe they might put some out later in the day.
Your daughter might be bored in there for three hours honestly. But it's a nice quiet place to hang out.
The wifi is the same free wifi everyone else in the airport uses, not that bad but not that great.
To me the best part of the lounge is that their newsstand is usually pretty decent. Mostly Spanish newspapers and magazine, but they do have some English ones.
Other than that, it's pretty basic. Not worth £25 in my opinion.