The phrase 'have a lot of knowledge' is perfectly correct and usable in written English. You can use this phrase when you want to indicate that someone possesses a great deal of information, or to talk about someone's depth of understanding in a certain subject. For example, "My grandfather has a lot of knowledge about the history of our town.".
"I have a lot of knowledge of skiing in particular," he quips.
"We find a lot of people here who have a lot of knowledge and skills which we can use".
"Private sector organisations have a lot of knowledge in this area, and they are focused on delivery," he said.
"The companies have a lot of knowledge about safety precautions, but they weren't always sure that their proposals would work.
He has a lot of knowledge about the game.
She has a lot of knowledge about the game".
Amaker had a lot of knowledge of how difficult Littlejohn Coliseum can be.
I love the desktop app, it’s always running on my Mac. Ludwig is the best English buddy, it answers my 100 queries per day and stays cool.
Cristina Valenza
Retail Lead Linguist @ Apple Inc.