I live in a rental property that has a tiny yard out back. I’d love to paint it just to brighten it up a little more for sitting out in the 3 days of UK sun, but don’t want the landlord to take a hissy fit and steal my deposit. So if I did paint it, is there a (easy) way to strip it before I leave? 
You can buy Ficus trees in pots (easy care, no mess, propagate easily) pretty much anywhere in the world on local market places (facebook, gumtree, craig's list, etc) and use them to block/soften the wall and bring in some colour i.e. green leaves + pot colour. A few of those with some string/fairy lights and poof ... endless tranquility! (individual experience may vary).
Example: