How would I go about getting this colour?

In my experience, these natural looking blondes are a bit hard to achieve at home. I'd say this is a level 6 or 5 but it's hard to say which shade exactly... most hair dye brands have slightly different shades so it's easier if you first pick the hair dye brand and then the colour.
I think it would be best to go to a professional. They have plenty of shades and samples so you can see which one would be the closest to the color you want and they can also make a mix if needed.

I would say in my completely non-professional opinion that it looks like light cool brown with dark to medium neutral blonde balayage highlights starting at about the ears down. In any case I agree that this is something difficult to do yourself.

I would say most of the highlights and lowlights are from colour saturation and contrast being boosted on the photo. Not something easy to achieve in reality.

see now on that model her hair looks fab, thats pretty much my natural colour only a bit less blonde on the lengths and i think it looks horrid on me!
Hmm, id agree, go to a hairdressers as for that sort of colour a home job is likely to be either too light or too dark, plus thats quite an ashy brown at the roots, and ive found it really hard to find any decent ashy browns in the shops that dont come out too dark... =)
I hate spending money on my hair in a salon as i know i can do it myself but for a job like that or for one that i know id struggle with its so worth getting it done professionally. =)

I have just achieved a similar colour on my daughters hair over a bleached base.. I used Nirvel Artx Nutre colour in Grey mixed with an orange i mixed myself and conditioner. An Adore dye in a natural ginger shade would be easier, and what I will use next time if she decides to keep it. The Nirvel grey is quite warm toned, so good for creating natural colours.