"In my impression" is correct and usable in written English.
You can use it to express your opinion about something. For example: "In my impression, the political situation in the country is getting worse."
"In my impression, he answered the questions honestly," he said.
"In my impression, Gu Kailai was a gentle and feeble woman; she couldn't possibly kill someone," Mr. Bo said.
Though we had the tree, our neighbors' trees were in my impression bushier, pressing against the ceiling and crowding the front windows, and more sumptuously hung with reflective balls, colored lights, and glittering tinsel.
I was confirmed in my impression of Toru as a person who lived his life like a traditional Zen poet".
Perhaps I could have defeated Lemon's thoughts in the confines of the play, but this would have given the audience the impression that in my opinion those thoughts had been safely buried at least for the evening and everyone could go home and sleep in peace, whereas actually I don't believe that . . . and so in fact to . . .
In fact my impression last night was that his audience was disappointed by his clever performance.
Mr. Penn told The New York Times in 2010, "My impression is that Yéle is at the service of Wyclef Jean and his reputation".
On the whole, while blogging and internet reviewing is taking hold in France, my impression is that it's less all-devouring, so to speak, than those things are here.
"In Franklin County, my impression is that there was no enforcement of this requirement," said Professor Foley, adding that he had heard reports from several other counties where the law apparently was not enforced.
In general, my impression is that employers are relying more on the written job materials and the interview to make a hiring decision and are using references as a final check.
Hathaway, who makes her living as a Hollywood actress, rather heartbreakingly told HuffPost in 2014, "My impression is that people needed a break from me". .
