Just because you’ve got a smartphone does not mean that you can pop a look at where the UKCAT test centre is just as you exit the supposed ‘nearest station (or bus stop)’.
Use Google maps (better still use Google street view) to locate your test centre well before your test day. One would hope that you chose the test centre based on proximity when you booked the test. Familiarity with location will help stem any unnecessary jitters that can be expected when going to an unfamiliar place. Also, knowing where you need to be to take the test is handy too!