Could you please elaborate when you say 'the web store looks a bit sparse and plain'? Do you mean there aren't that many products featured?
Well I guess it just comes down to personal preference but there are no containers or boxes focusing the eye towards the products and inner body content on the website. So the few items in each category get overwhelmed by the sea of white surrounding them - only a problem on desktops? Bigger product images might help too.
It's great that you're getting this enterprise going, you would need storage space at a minimum but a shop in London must entail massive overheads which can drain an internet startup unnecessarily. Good luck with it