London Paddington station will be closed to all traffic on Saturday and Sunday 28 and 29 November.
That means there will be no Heathrow Express and no Elizabeth Line services. The entire Elizabeth Line (Abbey Wood and Shenfield to Heathrow/Reading is currently advertised as closed, including the central core).
GWR long distance services are being diverted via Oxford and Milton Keynes (on the new line via Winslow) to London Euston (except the Sleeper which is being sent via Ascot and the West London Line).
Local services such as Paddington to Oxford are to and from Reading only, with London passengers diverted to South Western Railway services to Waterloo.