VAT is charged at three rates in the UK: 20%, 5% and 0%; so zero is definitely a number for VAT. However, zero-rated sales should not be confused with VAT-exempt sales.
Sales which are zero-rated must be included within your business turnover that counts towards the test for compulsory VAT registration, whereas exempt sales are not included in that total. This distinction is particularly important for new traders, whose turnover for a 12-month period can quickly exceed the VAT threshold (now £85,000).
It is worth checking with your suppliers how the goods you buy for resale are treated for VAT purposes, as there are some strange anomalies. Look carefully at your purchase invoices to check whether you have been charged VAT at 20% or 0%, or if the invoice says the product is exempt from VAT.
If you leave out zero-rated items when calculating your total sales for the last 12 months, you will understate your turnover and may fail to register for VAT on time. If this happens you will have to pay the VAT on sales made from the date you should have registered, and HMRC will charge you a penalty.