Grobags/ sleeping bags are brilliant. We have a very restless sleeper, and it not only keeps him confined, putting it on him in the first place is a kind of signal that it's time to go to bed, after which he is much more willing.
You can pick the baby up and, if you get the sort with "vents" for the straps (Grobag, JoJoMamanBebe and no doubt others have this), you can transfer baby from bed to car seat/ pram to bed and other combinations.
I can't recommend them enough, although I am not sure what it will be like, making the transition to "proper" bedding.
Hope this helps! Even if you don't get on with them, that's only one "size" wasted, not several years' worth of blankets. Good luck.
P.S. We have always had the sort without sleeves, as they are less hassle to put on, and we were scared of overheating in the early stages.