I need a Kotlin/Java app to send a single text

I want an app for Android phones with a single button that sends a text created from data collected on the same app's form.

It is dead simple. It will take a day max.

Just do it. Prove it works.
Field 1 = "hello".
Field 2 set as a space.
Field 2 = "world"
Field 3 = destination phone number (with appropriate checks to ensure it is a UK valid phone with 11 digits beginning with 07)

Give me access to edit the app published on Android. I will do the rest.

Any questions, email me, but only if you are the developer. We are in Oxfordshire. Where are you?