Last year I started my kids on swimming lessons, which really became a bone of contention between me and my 9yo as he suffers from anxiety and just began to hate his lessons more and more. It became that our whole week was ruled by his swimming lesson. Eventually I said to him that he didn't have to go back to swimming when the summer starts, he could tell me when he was ready to go back. We're not giving up, just putting it on hold. Then he decided he liked tennis, so I suggested that now he could start tennis lessons. He loved that idea, so I arranged for him to go to lessons at his school after class. To my surprise to find that ... he doesn't want to go.
Anyway I told him that the coach is expecting him and showed him where to go and said he must go and see if he likes it. Subconsciously thinking why have I got a kid who doesn't want to do ANYTHING??!??, and, I figure, my body language expressing, I've done this for you now you're GOING ... !
So the lesson is today. I told him that he would be fine. "Yes", he says "I'll be fine when I'm on the court, but I don't know anyone and I'm not sure how to find the courts". Oh. (He's like me, I have NO sense of direction, it doesn't matter of you show me 1000 times where to go I will still struggle when I do it on my own). I had the very same issue for the first two months of highschool. Every week I was late for maths because maths started after break and I couldn't find the class. It gave me stomachache so bad my mom kept me home a few days.
So I told him to ask his teacher who has a very good relationship with him to help him. He wouldn't let ME go and ask her as I guess he wants to deal with it on his own. But I feel very guilty that I thought he was just being oppositional when in fact he had a reason, and I have the same problem. Anyway I think it's dealt with but wish us luck.
Good luck! Another option for him is to maybe ask the coach to meet him part way? Is it a private lesson? I doubt the coach would mind as long as it is not disruptive to other children. If he ends up not liking it, dont get too discouraged. My daughter tried so many things and hated them all (mostly anxiety based), now starting at age 10 she rides horses! LOVES it. She'll never go the olympics, or compete in a horse show, she is too nervous to do much of a jump or go very fast, but she LOVES it and goes every week. She just enjoys being around the barn even just to helping the other kids tack up and brush thier horses down. Keep trying something will click for him if tennis isnt it.