I think it will depend on your baby. At least you will have a few things to try.
My DS was really long and the sling lying down in newborn style just didnt work for us. I am using it now that he can sit up though. I also use a baby wrap (google mama toto) where I wrap a piece of material around (similar to a HAB but a lot cheaper). It is quick to get a hang of and would have been perfect when he was a newborn because it is very supportive. Although DS was an autumn baby. If it gets really hot, you may find the pram to be the best option until the colder weather hits. Otherwise perhaps a sling. Play around and dont be disappointed if what you expected doesnt quite work as there is definitely a baby wearing option for most people.