I do wonder who signs off on the UX for the website. Again Citrus Lime decide to design something that is markedly different to most other websites, is harder to use and provides no benefit at all. Is it design for design sake?

Using the postcode lookup UX on checkout gives a pop up, with addresses in blocks or cards, in no particular order unless it's a house number and for postcodes with lots of potential matches further pages to navigate through. For one address I tested there were 3 pages of addresses to scan through! It's particularly bad for work addresses or house names rather than a standard street with numbered properties. Image attached is the example for Citrus Lime's Manchester office. 2 pages in no order that I can tell.

Using the postcode lookup should provide a drop down "choose your address" after search - in line rather than pop up, sorted numerically & alphabetically. Better still like most large sites, see Argos, M&S etc the address populates as you type, no search icon or further steps, again sorted logically.

Simplicity, familiarity and less frustration are key to a good checkout experience.