Highgate, N6, sits on the north-eastern side of Hampstead Heath. There's a small row of shops opposite Highgate tube station on Archway Road with two charity shops. MIND has been recently renovated; it's now more sparse, but pretty decent. It's like one big shop divided into two: there's a clothes and bric-a-brac part, then a side media room, consisting of books, CDs and records. I like it, though I've never bought anything there. Nearby RSPCA is reasonable if a bit tatty.
Uber posh Highgate Village is some way away from Highgate tube station and up a hill. The Cancer Research is average with quite a nice bric-a-brac section and lots of scarves. There's a charming Oxfam Books & Music, with an interesting selection of books and poor selection of CDs and records. It's pricey too – Richard Neville's book Playpower (which I would have paid £5 for) was, er, £50. Opposite is a regular Oxfam which also has some books and CDs.