In that case (and in my point of view), the correct sentence would be the one using "I'll try". Here's why: When you say that you'll try to come over, you're saying that you'll still make an attempt to attend; Now when you say that you'll have a go on it, you're saying that you'll attend in order to experience it. It's something like: "I'll try to come to your party, but I'm not sure if I'll make it on time." "I don't usually like parties, but I'll have a go on this one." Hope I was clear enough. Best regards.

In this context, I would say "I'll try to come" and I would never say "I'll have a go" I use the expression "I'll have a go" or "I'll give it a go" for situations when I am about to try something that someone else has been attempting. For instance, if your wife is trying to open a jar and asks for your help, you might respond "I'll have a go" or "I'll give it a go". I hope this helps.

I try to come es más como intentar de llegar en este caso I will try to come to your house this evenin. intenaré de llegar a su casa esta noche I´ll have a go es una expresión. se utiliza como intentar de hacer. I´ll have a go at swimming. Intentar de nadar, pero no estoy segura yo puedo hacerlo. I´ll have a go at playing football. tratar a hacer el fútbol. Más como intentar o tratar de hacer algo.