Future tense - bydda i'n vs fe fydda i

I’ve done all the SSI Welsh southern courses and now I’m watching ‘Now You’re Talking’ on Youtube. In episode 35, they teach ‘I will be’ as fe fydda i, whereas in the SSI Welsh course it’s taught as bydda i’n. In fact all the future tense forms with ‘will be’ are taught with this extra ‘fe’ at the beginning int ‘Not You’re Talking’, so I’m wondering what’s the difference and what is the most used, most natural version in everyday Welsh speech?

There is absolutely no difference in meaning between Fe fydda i and Bydda i. The Fe is a so-called “affirmative marker” that can be used in positive statements, and it causes a soft mutation. (You may also hear Mi fydda i instead, depending on region and/or speaker preference). All forms are equally likely to be used, so just choose the one you feel most comfortable with. You may also hear Fydda i in statements, where the marker fe/mi is lost, but the mutation is kept.