Hi,
Is this sentence correct? -- In as much as we would like to lend it to the city, but none of our canopy is available on the dates you requested.
No. Very generally speaking, 'in as much as' is used to say what you want to do, and the second part of the sentence says how you will do it, not why you will not do it.
eg In as much as Tom wanted to marry Mary, he asked her last night.
For your sentence, I suggest this.
We would like to lend a canopy to the city, but none of our canopies are available on the dates you requested.
Best wishes, Clive