I'm another sahm, no plans to go back to work until kiddywinks at school (though i went back to work when Oscar was 4 months old until i had Will so btdt as a working mum too)

No you don't have to join - just carry on as is - it's just an option of paid upgrade so you can have an avatar, bellybelly email, post in a few different forums and a few more things i'm sure.
I know what cookies are but can't really explain so maybe let someone else do that (aprt from the tasty choc chip ones mmmm - now im just being silly)

Julie x