UniFi records all locally, and you can either use local only accounts (no cloud) or enable cloud access so that you can still get notifications and things when away but all video is still done locally and so it wont take a lot of your bandwidth unless you are actively watching a video stream remotely.
I would get a UNVR Pro as their NVRs start getting a bit laggy after you pass 50% camera capacity. Or a UNVR G2 if you want to add some AI natual language searching for footage.
And you get stick with G5 Turret Ultra and G5 bullet cameras which have nice picture and are relatively cheap cameras, or step up to G6 Turrets if you want higher resolution and AI facial detection for your alerts. You may want to use a single G6 in certain areas like a driveway, near the front door, near the back door to make use of facial recognition alerts (so and so is home, etc) and then G5 Turret Ultras everywhere else to save money.