While site plugins are indeed available if you don't have the skills then you have to purchase the relevant skills to apply them, none of this is cheap and trying to apply to an existing site is not straightforward. In our own experience of trying to apply a shop and other facilities we've had to scrap the existing site and build a new one as the existing is unsupported after just 4 years.
Whenever businesses are sold on there are problems and issues, with the best will on both sides these can't be avoided. I'm willing to give Phil some time to find a way that works for him, and as a customer that has purchased £4k+ plus (from C&L) in the last few years, and likely to purchase more, I want him to succeed, but in a way that means he can continue trading long term.
Slightly off at tangent, but for a working website where you can order what you like and pay for it seamlessly how about this one.
http://shop.cooper-craft.co.uk/index.php?cPath=61
Probably better if you didn't though.