Cot Bed or Swinging Crib?

Victoria
I still have a spare single bed in my house so was going to make that the baby bed once he gets bigger but not sure if I should still get a cot bed to trap him in when he is a toddler and save him getting up in the middle of the night. Aagghhhh!! 
So thinking I could get a newborn swinging bed crib which could be nice and soothing for baby and get rails for the single bed for later. Will he need the intermediate toddler bed? Are guard rails enough for a single bed? Will he be better off without being confined behind bars at night but just a guard rail? Most guard rails don't go all around just stop them rolling out!