No, International text messages are not included with my plan. I found this out by trying to manually text the +44 number and having it not go through. I called customer support and they said international text messages were not included in my $40.00 plan and that if I wanted to send them I would have to top up my account OR travel to the United States (...really odd).
Anyway, I added $5.00 to my Wind account, restarted both iMessage and FaceTime and then waited a couple minutes before commencing the *5005*78283# code. Once in the log file, I did a ctrl+f and searched "point to point" and immediately found it!
I would ensure you indeed have international texts included in your plan. Try sending a text manually to the +44 number. If it fails, you may need to top up your account.