First Baby – Do I need blankets aswell as grobag?

I think using a sleeping bag for my baby, but I know that I can not go on until a £ 10 so the plan was to use a cover band before their first born. I need extra blankets, like this? Even if you use a sleeping bag has yet been set foot on the bottom of the baby crib, even if they are not able to go under the sleeping bag? A grobag sleeping bag is a special children SIDS recommended by the association to be safer for the child (Sudden Infant Death Syndrome Association) – I’ve read all the information that nobody else has? read that you should be with the baby in the crib with your feet down there so that can not escape down under the covers and suffocate?