HOWEVER, a business can only advertise prices net of VAT if the majority of their business will be to trade (ie VAT registered) businesses.
This is why Matalan when they first started out offered their services net of VAT, but had to change their pricing in store as the majority of their customers were retail.
Whilst you will probably have to pay the VAT in this case, it may be worth emailing them to ask what sort of percentage of their business is to the trade and if you are unhappy you can contact your local trading standards.