I was bored so I decided to send a message on my phone to a random number for a laugh.
I said 'Did you bury that prick Billy's body'
It was just banter, but am ****ting myself that the police are going to come after me.
What should I do?
Short Answer: Yes
Long Answer: You're f****d mate
The person you sent it to will almost certainly report it to the police.
Holy ****, you're not in hiding already? :O
Could you get in trouble? yes. Will you get in trouble? Probably not.
If I were you, I would text the person again and say "sorry that was my friend he was trying to be funny" or something like that and you could also inform the local police that you sent a text as a joke but could be seen as evidence of criminal activity.
I guess you should but that will only reduce the chance of being reported by an insignificant amount. Face it. Your going away for a long long time.
It doesn't matter if the person reported you as it is likely that you are under investigation from GCHQ anyway.