I'm not a VAT expert, but here are my 2 cents in a nutshell based on commercial dealing in belgium and france (which could entirely have different rules than the U.K.).
In theory, products for export are generally exempt from VAT, meaning that the manufacturer/seller does not have to charge/collect VAT from the "next in line." however, i'm not sure how certain VAT regulations deal with internet sales. unless there is a specific rule out there, this could be interpreted in 2 ways: (1) an online sale is treated as a walk-in sales, thereby attracting a VAT; or (2) as long as proper records for sales are maintained (i.e. who bought what from where), then certain overseas sales may not attract a VAT.
If a company is playing it conservative, they'd go with interpretation 1 above.