You can also use ‘going to + the infinitive’ when there is a clear intention. ‘Will’ is only used for things like promises and offers about the future.

In any case, I am being pedantic as people with a good knowledge of English never need to think about these rules. They are there for the benefit of people for whom English is a foreign language.

Glenn Bedingfield would do well to pick up a book on these elementary rules before he tries to write.