Thanks guys for your responses. Some great discussion. I definitely need a lawyer or alternatively might just develop my idea in secret and leave on completion for clarity.

I have established a LLC before I was employed by another company. The company was fine with me having both a job with them plus running my LLC after checking with legal. The IP assignments clause was a little murky hence the original question.

I knew I should have requested a contract amendment but I was desperately trying to get a job at the start of the pandemic.