The institute is located in the Ogden Centre for Fundamental Physics, adjacent to the main Physics department building (Rochester building).
If you are arriving in Durham by train, the train station is a 20 minute walk to the Science Site. Otherwise you can take a taxi (there are taxis outside platform 2 or you can get an Uber).
The closest airport to Durham is Newcastle (NCL). From there you can either take a taxi to Durham or the metro to Newcastle rail station and from there a local train to Durham.