As far as I know this sentence is well constructed:
I'm going to be in England next week.
I know it is wrong to think that certain English expressions must adjust to Spanish logic since they are two very different languages; having said that, I would like to understand why the verb to be is used twice? I can understand the presence of the personal pronoun I and that of the verb to be the second time it appears, but why do we have to conjugate it the first time (I am going…)?
Best Answer
I'm in England next week is perfectly grammatical. It relies upon "next week" to express the idea of the future while using present tense. I believe that is what you had in mind when referring to what can be said in Spanish.
But we can express the future in another way too.
We can say
Let's work backwards. The sentence with "am going to be" has a finite BE and a non-finite BE.
to be in England refers to a non-finite (i.e. outside of chronological time) existential/locative state, namely (being)-there-in-England.
Now, put going in front of the above, and you project that non-finite existential/locative state into the future, since going + infinitive places the action or state of the verb in the future:
going to be in England, namely, in-future-(being)-there-in-England.
Now, put I am in front of that, and you complement the bald existential statement "I am" with the existential/locative "in-future-(being)-there-in-England".
In other words, your current intention is to be in England next week.