On The Getaway's first D.C. Carter mission (which is mission 13 I think), the starting point is at map grid E4 on the B&B London City Center Map, 11-B1 in Eyewitness Travel Guide London. It seems to be on either Brendon or Forset St. (hard to tell because not all the minor streets are in the game). The destination is the University Hospital (D8 in B&B, 5-A4 in Eyewitness). The big green dome on the left that you speed by is the Planetarium (assuming you follow the recommended route blocked off for you by the other cops).