Several of the Trichocereus, recently renamed Echinopsis, group cacti (pachanoi=San Pedro, bridgesii=achuma, etc) are high elevation cacti used to more cloud cover, cooler temps and higher precipitation than their low desert-based cousins, so UK should be fine as long as you bring them in during the winter.  In fact, near sea level in southern California I actually sunburned some specimens this past summer...imagine: an entire 1/4 of the plant becomes pale white and presumably free of alkaloids.