While my truck starts pretty good without the block heater here it is nice to have it and I do use it when I have electricity and it is going to be cold. At home I bought a timer that plugs into the outlet then plug the heater into that. Have it set to come on at about 3am and to shut off at 7am. I usually leave around 6.
I would certainly buy the cord it is easy to install. I would also take a look at Genos Garage for the cord and they have a snazzy little plug receptacle that goes on your bumper so you are not fishing around for the plug and it includes the cord.
https://www.genosgarage.com/product/wd-bhp-10/winter