Guildford is easily reached by rail. There are two stations: Guildford railway station is nearest to the university and is 35 minutes from London, Waterloo if you take the fast Portsmouth Harbour train. If you are staying at the Mandolay you should consider Guildford London Road instead, which is about one hour from Waterloo on the slow train but you avoid walking up the hill.
From Guildford railway station, when you get off the train go up the stairs to the bridge across the platforms. Turn left to exit the west side of the station. Turn right onto Guildford Park Road, then after about 100m turn right on Perimeter Road. Follow this to the north, through the car park, to enter the campus at its south entrance. Follow Perimeter Road around until you reach Spine Road on your left. Head up Spine Road: the BC ("James Joule") building is on your right. Go up two floors until you reach the "third" floor. Walk around until you find 30BC03 (30 is the room number, 03 is the floor number).
If you come by car, good luck. Traffic and parking are both a nightmare. Rob can possibly negotiate for parking spaces.
Travel from nearby airports is relatively easy. There are direct trains from Gatwick to Guildford, and there is a bus from Heathrow although a taxi is also a reasonable option if booked in advance e.g. through Beeline.
For those coming to Guildford in person, try the Angel, Mandolay and Harbour hotels. Cheaper but more distant options are the Travelodge and Premier Inn. There are also bed and breakfasts dotted around the university which are usually good (this one is recommended by colleagues).
There are plenty of food and drink places on campus, see e.g. here for more information. In the evenings we will dine out.