The Explorers make several weekend trips throughout the year to North Wales, the Lake District, Scotland and the Peak District. During each trip there's pretty much always some rock climbing and hill-walking going on. During the coldest months some of them go ice-climbing. Occasionally there's mountain biking too.
There's indoor climbing at the Nottingham Climbing Centre each Wednesday if that's your thing and there's a social on Tuesdays at Cripps bar (at least that's when and where it was last year).
Dave-o - Most of the more technical equipment is supplied, on most trips you'd need the right clothing and footwear for the weather (ie waterproofs, warm layers, decent pair of hiking boots), a warm sleeping bag etc. The society can provide tents, stoves, climbing equipment, ropes, maps etc.
Check it out at the Freshers Fayre!