Hey from the UK! Welcome to BYC it's lovely to have you here lots of useful knowledge and advice on here and everyone trys to assist with any questions or queries.
XxSamXx
Welcome here Andrea. What is your environment like cold hot that should help decide what breeds.
I picked mine because I needed them to be cold and heat hardy. I was also looking for egg layer breeds. My first chicks came from a hatchery and last batch I got at my local farm store. My farm stores here are having "chick days" ( but don't go until your serious as those little buggers will suck you in!)
I too collected rain water but couldn't screen it well enough and it gets skanky smelling after awhile. Just fyi.