good sound advice Baz, Nik I am with Baz on this you get a strong bond with a pup, you want to tie getting a pup in when you are at home for a lengthy period, that bond will never be broken, with a older dog you are miles behind, you have missed all the excitement and going from scratch, someone will have already been the dogs world or on the other hand it could be riddled with problems.
I think for your needs a nice well bred lab will be ideal, springers in my opinion need more than that walk around the block when you can't be bothered, they need 100% commitment.
You have every reaso