So you set your Magento shop to have vat as a tax class and you’ve entered all your products into the back end using the vat inclusive price. So far so good.
But when you add a product to the basket and then checkout your including vat price suddenly has vat added on again.
The main cause of this issue is that in Configuration / Shipping Settings / Origin
The origin is setup as United States which is the default setting and you’re in the UK
So Change Country to United Kingdom in Configuration / Shipping Settings / Origin and your problem should be solved.
If not drop us an email and we will help you solve it.