Forcing calculate shipping on cart page, blocking checkout until calculated

Hi there

I’d like to know how to force customers to click on Calculate Shipping and select a shipping method before they are able to checkout their order.

My client (website brand owners) is offering several delivery options, including courier at a premium rate, standard post office shipping, customer collection on site and free shipping for orders over a set amount.

The problem is customers don’t seem to be aware of the ability to select their shipping option and I’m seeing a high drop-off rate between cart and checkout steps, due to courier being the default shipping cost added to the cart total. For smaller products, the cost of shipping can exceed that of the actual item, which deters shoppers.

If possible, I’d like a popup to notify them that they have to calculate their shipping option before being able to check out.

URL: https://www.poptex.co.za