Will a 4.5-5 year age gap be okay?

We were set on one child and our boy is now 3.5, we are thinking of having another as I think in many years we will regret not having 2. However it's been very hard as we don't get much support around us which is why it has took us so long to decide.

Will having a 5 year old and a newborn be okay or will it be insanely hard work?

Also is there any chance they may eventually play with each other a bit later down the line?