1. When you are going to attend your very next seminar coming up next month, can you say the following? Shoud I just follow the norm and go with phrase "next month's" almost every time?

"I am planning to go to the next month's seminar," instead of the usual phrase,

"I am planning to go to next month's seminar."

2. How would you put the determiner under this kind of situation?

There is an??? "E" in your first ...

There is a??? "X" in your first ...
It sounds very odd with the article. Is there a reason you want the article? If you want to emphasize that it's the next one, then say "I am planning to go to the next seminar, in July."

2. Yes, you would use the article. Both take "an." An ee, an ecks is how it would sound. These get "a": B, C, D, G, J, K, P, Q, T, U, V, W, Y, Z These get "an": A, E, F, H, I, L, M, N, O, S, X
I agree with GG.

The might introduce just too much specificity, as you have already next month's there.
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Hi Marius,

Thank you.

Can I change your sentence like this and could it still make sense?

The might introduce just too much of specificity, ...

Can you tell me when it is appropriate to use "much of an uncountable" and when it is to use "much "?