In the UK the colour choices for the mk7.5 GTI And R models in the UK are;
GTI - Pure White, Black Rubin, Tornado Red, White Silver, Atlantic Blue, Tungsten Silver, Indium Grey, Isaac Blue, Deep Black Pearl and Oryx White. Black Rubin is the ‘standard’ no-cost colour on the GTI; all the other available colours are an extra cost option
R - Pure White, Tornado Red, White Silver, Atlantic Blue, Indium Grey, Turmeric Yellow, Deep Black Pearl and Lapiz Blue. Pure White is the standard no-cost colour; the other available colours are an extra cost option.
Not a very exciting colour palette, unless you’re getting an R and you’re brave enough to go for Turmeric Yellow, which IMO looks good in bright lighting conditions, but not so good in dull, overcast light. Turmeric Yellow won’t appeal to everyone though.
The custom colours aren’t available in the UK.