How to tell a male friend that you dnt want to take the friendship to the next level AND NEVER WILL?

I need your advice people.I recently met a man while out walking my dog. We got talking and we ended up having a really good and deep conversation and I felt like I'd known him for years. He said I seemed like a great girl so maybe I'd like to go for a meal with some of his mates the next day and invited me to bring friends along. I agreed and all his friends were lovely and my friends commented on what a lovely guy he is. Now no doubt he is a lovely guy and I feel a real connection with him. However in his texts (not in person) he will call me "y", "babee", "hot" etc and he has kinda hinted that he would like to go on a date with me. Now I dnt mean to be nasty but I am an 18yo student and he is 40 and overweight and he defo hasn't aged well! I would never ever consider him as a romantic partner EVER. I have told him this EVER bluntly and even said I have a boyfriend but he still makes ual remarks and comments continuously on how fit I am! I think in his own deluded (and pervy) mind he thinks there's a chance I'll like him. At his age he sould not even be after a girl of 18. How can I make him absolutely clear that nothing romantic will EVER happen