I think I'm charity shop addict... especially since I had Odessa. We regularly go together to our local ones, since the nice ladies working there let her play with all the toys, which keeps very busy and I can calmly do my treasure hunt. I live in Wandsworth where you can find a few "Fara Kids" which are charity shops with only baby and children stuff. It's a great place to find cheap toys and affordable designer clothes. You can also buy prams, high chairs, a large selection of books etc.. In Notting Hill there is a Fara Kids which specialize in vintage toys - definitely worth visit.
And this is what I found a few days ego: Gap cardigan- lovely colour looks beautiful with short dress £4.80, Cath Kidston kids bag -£1.80 - perfect for Odessa's lunch as she is going start her nursery this month and (of course, no surprise) a rabbit for 85p ('Guess how much I love you') and it's perfect for erm, being a rabbit.
Of course the money you spend goes towards helping those who need it; Fara collects money for orphaned and abandoned children in Romania.