Updates can be a problem if you have a limited data allowance.
Especially if using Windows 10.
If this applies to you then set your connection to be a 'Metered connection'.
If your using Windows 10, open your 'Network and internet' settings from the system tray and click on 'properties' for the network you are connected to.
A window will open where you can set the metered connection.
This will stop Windows updates/upgrades from downloading Automatically and eating your data allowance while you are connected to that network.
(They say some 'critical' downloads will still happen).
When there is an update to install (second Tuesday of every month, and a bigger one about every six months) you'll get a notification.
Find your nearest pub/cafe with free wifi and take your laptop/tablet to do the update while you have a few drinks.
(It can take a couple of hours for the bigger updates).
As for other software, most programmes let you turn off automatic updates or update checking, but you'll have to check for each programme you have installed.
One other tip: get an adblocker for your browser, or use a browser that has one included as standard.
Adverts also eat your data allowance as they download to the your computer, especially video adverts.