Wolfson College is about 2 miles from Oxford station. If you have 45 minutes to spare, the walk through University Parks and North Oxford can be pleasant. The Google directions can be found here. Alternatively, it is a taxi ride of about 5-10 minutes.
If you are arriving by bus, the bus station is near the centre of Oxford, and and about 5 minutes less to walk.
There is car parking available at Wolfson College, but if this fills up there is some 3-hour on-street parking nearby that becomes available for unrestricted use at 6PM. The traffic leaving Oxford will probably be very heavy about this time, but coming in to Oxford will hopefully be bearable. Be aware that there are road works on the Northern section of the Oxford ring road on the A40 between Wolvercote and Cutteslowe roundabouts. Expect traffic in this area to be slow.
Please note that the train service between Didcot and Oxford (affecting services from London Paddington) is suspended from 30 July to 14 August, with a replacement bus service operating between Oxford and Didcot. There are also railway engineering works taking place to the north of Oxford.
For anyone travelling from further afield, there may be bed-and-breakfast accommodation available at Wolfson College: see the Wolfson College page about visitor accommodation.