Both services pick up at Marble Arch. The Oxford coach station is about half a mile from the Department - see city centre map below. A period return ticket will be about 12. There is a free shuttle service between Terminal 4 and the other terminals. A taxi from Heathrow to Oxford will cost you about 50.
Most taxis take four passengers.
This is a rather expensive way of arriving at Oxford. If you approach Oxford from the east on the M40 you should leave at junction 8 or, from the north at junction 9 - see maps below. Those traveling on the M4 should get off at junction 13, Newbury, and take the A34 north to Oxford. The Physics Department is in various buildings within the Science Area of the University. There is on-street parking available in Keble Road which is close to all our buildings.