I have 2 at Broomwood and agree it is a very warm inclusive school with lots of working parents.
If you are looking for boys then I wouldn't worry too much about Northcote Lodge yet, concentrate on Broomwood. Most boys do go on to Northcote but lots also do the 7+ and move to day schools at that point: KCS, Dulwich, Alleyns, DPL ....
Interesting what ByeByeSunshine says but not actually sure it is very true.
I did a very detailed comparison of leavers destinations for Eton House, Thomas's, Broomwood and Newton over the last 10 years when we were choosing between them (I appreciate this makes me look very sad) and there wasn't much in it in at all in terms of numbers of boys going off to the very top schools (Westminster, Winchester, Eton, KCS...).
Where the difference lies in which mid-range schools they send them to - which of course is where the majority will go.
Northcote packs them off to the boarding schools with Charterhouse, Harrow, Wellington and Marlborough being the most common destinations. Thomas's boys more normally go on to day schools and Emmanuel, Dulwich and Alleyns get most leavers. Eton House broadly splits between day and boarding but the schools that get most boys are the same.
The conclusion I reached was that actually they all get a few boys into the very top schools and the rest into good schools. I think it pretty much follows the percentage of very clever boys you would get generally so school choice is not so critical.