If your delivery postcode is being rejected please first check that the Warehouse website is set to the same country as you wish to delivery to. For example, if you wish to deliver to Ireland you will need to check out on the Irish website. This can be checked on any page (except checkout pages). At the bottom-right-hand-side of the page will be a flag indicating the country the website is set to. If you need to change the country, simply click on the flag and select the country you wish us to deliver to.
If you are still experiencing problems, please contact customer service here.