After all day of research I finally found 'Desert tan' in the UK.
http://www.humbrol.com/237-desert-tan-matt-150ml-acrylic-spray-paint.html
I hope this will be good enough.
As for the olive green which is recommended, I couldn't find the exact one on humbrol's website.
Will this one be good enough?
http://www.humbrol.com/155-olive-drab-matt-14ml-enamel-paint.html