punctuation - Comma before where when the clause is at the end of the sentence

Please tell me if I should place a comma before the word where in the two sentences below.

1. I would like to work for you since I’m interested in working in a leading international school with excellent reputation where I can utilize my skills and knowledge.




2. I have about 3 years of experience and, at the moment, am developing specialized courses in Healthcare, which became possible by virtue of my studying at an international school, where all sciences are taught in English.

Here is the link with one of the articles I consulted with, but I only get more confused:

http://www.chompchomp.com/terms/essentialclause.htm

As I understand it, in the first sentence I put the comma, because if I remove the clause, even though it will be a stand-alone sentence, the meaning will slightly change.

The second sentence: on one hand, I thought I ought to put a comma if if I'm specifying (the school) what I'm talking about. On the other, it's essential information, and, therefore, the clause should not be preceeded by a comma.

The nouns are ambiguous in both sentences, which is the case when we use commas to spesify. However, for me, in both cases the information in the relative clause is necessary and I understand we do not put commas before essential clauses.

Can you clarify when we put a comma before where if the clause is at the end of the sentence.