Can CSS be used for conditional pricing model?

Site URL: https://www.vinobliss.com

Hi,

I am selling a product from France to United Kingdom, and we have different prices based on the amount of product sold and the postal code within UK that it's being shipped. I cannot find a way to write a conditional pricing formula in Squarespace since you can only go by postal code for US and Canada. Does anyone know if this can be done, and if it can, who can possibly do it? I am happy to pay to have this set up!! Thank you!