Since updating my iOS, I can’t send a text message to people without an apple device.

If you have an iPhone - and both iPad and iPhone are signed-in to iCloud with the same AppleID - to send and receive SMS/MMS messages (green bubbles) from your iPad you must explicitly enable Text Message Forwarding for your iPad on your iPhone...

On your iPhone:

Settings > Messages > Text Message Forwarding - set to ON - and explicitly enable your iPad from the list of devices.

Also ensure that Messages in iCloud is enabled on both your iPhone and iPad:

Settings > [Your Name / AppleID] > Messages - set to ON

On your iPhone open the Settings App. Tap Messages. Make sure the following is checked:

1. SMS and MMS are turned on
2. Make sure your iPad is selected in Text Message Forwarding