A Roof Box is great, especially this time of year when you could be using your car to go on road trips to the country and maybe even camping. It provides extra space which you just don't get with all car boots.
When it comes to choosing one there are many options, but I like this Thule Roof Box at Essex Auto Parts, where it's on offer at the moment. Also don't forget you will need to also buy Roof Bars to fit the Roof Box to. Thule Roof Boxes fit 95% of vehicle makers and models. The Thule Pacific 100 Roof box comes in 4 different sizes, it has a fast grip system which makes fitting the box incredibly easy.
I suppose the sourcing and purchasing of a Roof Box seems easy compared to the thought of fitting one, but you shouldn't worry; it's quiet easy really.
Remember to obviously follow the instructions that come with the product and keep the following in mind. Ensure you place the Roof box centrally to make sure there's even weight distribution. The box should be positioned parallel to the road to reduce uplift. If you're fitting the box onto an estate car or a hatchback remember to leave enough space for the boot lid to open.