That sentence is grammatically correct.
The correct grammar for the sentence is: "Please note that this letter is merely an inquiry regarding your interest and availability."
I'll need just a moment to check the doctor's availability for you.
Yes.
There is no 'following sentence'.
CHIEFS, example sentence: The city fire chiefs held a meeting regarding the newest regulations.
I have a weird interest in exploration
No, that sentence is not grammatically correct. Availability is a noun meaning how much of something is there to be used. You could say "What is the availability of this job?" or "Is this job available?" or "Is this job still open?"
In the above sentence the word regarding is used correctly.
His interest was in photography but he could not pursue. it. It is an example of interest word sentence.
I'll need just a moment to check the doctor's availability for you.
Yes. Example: Regarding the previous test... Regarding next week's party...
My parents are very anxious regarding my study
My family has a interest in sports.
A good topic can interest people. If you are writing a report, choosing a good topic sentence will interest you, and your reader. It is very important to choose a good topic sentence for the interest of you, and the people who will be listening to you.
"The promptness of delivery of your order is subject to availability in our warehouse."
Can't see the following sentence anywhere
The saver lost interest in the investment once the interest rate fell to 0.5 percent.
No DoD official shall authorize or create any obligation or make any expenditure beyond the amount permitted under any statutory limitation that modifies or restricts the availability of funds.