Unfortunately, English is not really my strong point. I apologise, but I will be presenting in Japanese because my English would be difficult to listen to.
Unfortunately, I am not good at English. I don't want to make everyone uncomfortable with my English; therefore, I'm sorry but I would like to make a presentation in Japanese.
Unfortunately, I'm not very good at English. My English would be very difficult to understand, so I apologize, but you'll have to make the announcement in Japanese for me.