Chemical Engineering is absolutely not more chemistry than maths and physics. This is a common misconception.
Chemical engineering is primarily mathematics, followed by physics, then biology, with economics and chemistry forming the final, smallest portion.
Rate equations are basically the only chemistry we do. Everything else is solving ODEs, modelling reactions and optimising designs.
If you have an offer, they clearly think you're capable, so don't be discouraged! But again, maths is a big part of it - if you find maths hard going, you will struggle.
That being said, work hard, and you'll be able to work it out. It's only a smidge trickier than A-Level maths, you'll likely cover it all in your foundation year.
Any more questions, feel free to get in touch ☺️