Well, she's already eating cheese on Tuesdays.

You use "el" before days

All days of the week are masculine in Spanish, and they're not optional.

Yes. All days of the week are masculine and the article is not optional.

No el is correct. All days of the week are masculine, and the article isn't optional.

Whenever you use "voy" to say you're going to do something, you follow it with the preposition "a". If you think of it as movement, it's easier to remember.

"Martes" is a the name of the day, the S is not for plural it's just part of the name.

No, en martes is ungrammatical. You use el with weekdays to mean "on that day".

'Martes' isn't inherently plural just because it ends in an 's'. 'Tuesday' is translated to 'martes' and there is no 'marte' so the only way that one can know if the speaker is talking about a specific Tuesday or just Tuesdays in general is implied with the use of a plural or singular article. Los martes = 'Tuesdays' y el martes = 'Tuesday'.

That is just the way Spanish works "martes" can be Tuseday of Tuesday, depending on the use of "El" (used here) or "los" "On Tuesdays" is "Los martes."

En español, los días se nombran de igual manera en plural o singular, lo que cambia es el articulo que lo acompaña, el (singular)- los (plural)

There is only one conjugated verb per clause, and that space is taken up by voy already. The other verbs have to be infinitive. Just like in English.

As i genuinely want to learn different foods, not trying to pick at the 'chicken' eating thing

Just to clear it up: the preferred translation is "El martes voy a comer pollo." But "voy a tomar" is correct, too. Just like drinking something can be expressed with tomar, so can eating something.

The a here belongs to the construction "ir a" which is the Spanish equivalent of the English "going to".

There is one thing wrong with it. :)

The construction "ir a [verb]" is pretty much what "going to" is in English and has rarely something to do with actual moving. Rather, it's an expression to describe the immediate and/or planned future.

Your sentence could be translated as "El martes me voy para comer pollo." - "On Tuesday I go (in order) to eat chicken."

You need to know two things - which person (or thing) is doing something in the clause, and how many verbs are in the clause.

You should already know that first item - it depends on whether the person doing something (the subject of the sentence) is the speaker themself (I, yo), the listener (you, tú) or someone or something else (he/she/it, él/ella); or a group including the speaker (we, nosotros/-as), including the listener (you, vosotros/-as), or none of them (they, ellos/ellas).

Depending on that, each verb gets various suffixes indicating who does the thing, and since those suffixes are unambiguous most of the time, you can generally leave out the subject pronoun. For the verb comer it looks like this:

• yo como
• tú comes
• él/ella/usted come
• nosotros/-as comemos
• vosotros/-as coméis
• ellos/ellas/ustedes comen

Now the second item is important in this sentence. If you have multiple verbs in a clause (for instance a modal verb like "can", "must", "should", and a full verb), only the first verb is conjugated - the rest stays in its infinitive form. That's why you got "voy a comer" here: voy is the yo-form of the verb ir, and comer stays unchanged. Like in English: I am (conjugated) going (participle) to eat (infinitive).