Welcome Fuzzpig. It's pretty daunting getting started, but just take it in small chunks as others have said. I don't stock up loads to take to the charity shop, I just fill up and drop off one carrier bag at a time. It gets the stuff out of the house, but it's not piling up and getting in the way.
Re: body lotion and hand cream - I never, ever use body lotion, and yet you always get it in sets of smellies. I read on another thread this week that someone recommended using it instead of shaving gel / cream. Might be worth a go? I plan to try it, but shaving my legs is a bit of a mission at the moment (31wks pg).
Alark It sounds like the boden dresses were more what you were initially looking for, so if you think you have bought more than you needed, maybe take the mothercare ones back? But if you think they are needed and will be used, go with the "one in, one out" policy, and get rid of some older things. I don't think you should be annoyed with yourself, especially considering they will likely be used by your other DD too.
Nishi I'm a bit ruthless with freecycle collections, I tend to tell people things need to be gone urgently and make it clear that it will go to the first person who can collect it. I always put "collect from..." on my listings but get no end of people asking if I'm ever in X town, or saying they can't get over this way for a week or so. I normally apologise that I won't be able to hold the item for them but tell them to drop me a message nearer the time and if it's still available they can have it.