Well, I did the same as you Countrymum, havingno idea about Russell Group universities (even though my older son had already been to university many years before). As a consequence we too went with the school which was right for DD, not based on which schools get the most pupils into 'X', 'Y' and 'Z' universities.
Since that time I have learned loads from this forum and at one point I too wondered if more consideration should have been given. However, I think we also need to balance all the figures out with how the universities are now (apparently) trying to be more open and inclusive with their selection process, with many more entrants coming from state schools (albeit lesser achieving state schools).
I truly think we can only chose what is appropriate at the time, to do less would possibly means years of misery for our children in schools they didn't like, weren't the right fit for them and, at the end of that time, they possibly still wouldn't get into t Russell Group university.
Oh, and just one more thing, Russell Grou universities aren't 'all that' if they don'toffer the course your child wants to study and some other universities are actually better at the courses on offer than RG unis (not that I could name them
) - just a couple of points to bear in mind.