I don't think she does really think it's unfair - she seems to accept that boys are better (isn't there something about her imagining a family of all boys?). I don't remember anything in the holiday books. Although she's not really tested - she is fairly resourceful, but then no-one expects her to be, Her and Rowan do so off their own bats, while Peter's pressured into being a Navy type.

Karen is friends with Margaret Jessop, who Lawrie has a crush on. Lawrie also makes rather dubious friends left to her own devices - I suspect that prior to Tim, she hid behind Nick's friend-making abilities and tastes. At the Merricks' 12th Night party she's on the stairs with older and drunker people, and actually in The Thuggery Affair, she's enjoying herself thoroughly until she realises that she's been rather stupid in underestimating Red Ted.