It is very common for me to hear people all over the world complain about how they do not possess great grammar skills. Admitting that your grammar is not good in a negative manner is akin to saying that you are incredibly nervous and worried about your speaking. There is no need to be!
If you are speaking in a language that is not your first, people will be willing to give you some allowances and cut you some slack, especially if you have something interesting and useful to say. If you are delivering entertaining and beneficial information to the audience, they are not going to care about your grammar no matter how faulty it is.
Here, in the United States, we have had several presidents and politicians running for the office who have mangled their grammar in their public addresses and speeches yet it has never seemed to hurt them in the polls. They have been able to communicate effectively despite this lacking. So, if you are speaking in a language that is not your first, having good grammar is a bonus but not a priority. Your first priority should be to deliver interesting ideas with passion and excitement. Do not let your lack of perfect grammar keep you from speaking; if you have a great message, put it out there regardless.