u can not split ur business and just do commercial with the vat, if the vat man finds out and thinks u r coning him, customs and exercise are not the type of people u want to annoy, they can come to ur business and claim everything they have more power than the inland revenue, a lot of things got moved around and different dept where given a lot of power, when they raid you they only have the police there so you dont run off, my aunt was raided by them and they know everything that was goign in and out of her banks for years
also if you have to claim vat back, u have to pay them the vat u owe them before they will pay you