It sounds quite absurd - to just go for a walk with no particular direction. Simply leave the house and start walking. Turn your phone off and disconnect from the world for an hour or two and walk through London. It's not the most obvious of places to go for a walk, but even if you live centrally you're bound to come across something you've never seen before, or see something you've already seen, but from a new perspective.
It can be an effective stress reliever when the strains and anxieties of student life build up. People think students have it easy without responsibilities, but often students have a lot going on. Especially at a university like UAL where there is such a consistently high level of work being produced - students take it seriously and put the hours in. It can take its toll. Sometimes you need a break from it.
That's why you should go for a walk in London, ideally somewhere you don't know that well. That doesn't mean you can't walk in your own neighbourhood. Living somewhere doesn't mean you know the area comprehensively. You should just wonder taking a direction you feel impelled by. If you see something interesting then go and investigate. It's easy to get into a pattern in London, of seeing the same people and going to the same places. A directionless walk takes you away from that pattern. Hopefully you'll feel refreshed afterwards.