This might be worthwhile to consider for cost reasons:
http://www.invinca-shield.com/asp/genkit.asp?kit=3646

Phone: +1.336.838.5947 (NC)

It's the 987 Invinca Boxster S kit, but ordered from the US which might save some money. The full deluxe kit plus mirrors, delivered to the UK, should thus cost around 220-250 GBP (with the global delivery fee ranging between 17 and 32 USD).

The drawback being that ordering from overseas likely means self-installation, which could be tricky for some parts (bumper?). I called the company and they confirmed that every order of a standard, deluxe or options package comes with an installation kit and instructions.