Rather than list some landmarks and vehicles, there is one key difference which I would hope is reflected in the London DLC.
On my visits to European cities, I've always noticed how mixed-purpose many of the buildings are. A single building will easily contain a shop on the ground floor, a business or two on the next floors, and a variety of apartments above. This is how it's modelled in CiM, which does a great job of recreating traditional European buildings. I'm sure this mixed-use aspect isn't always the case with the buildings in Europe, but it's a difference that struck me.
The difference is because in the UK, it's less common to have such multi-purpose buildings. Buildings, and whole areas, are frequently single-purpose. Either residential, or commercial.
This has an obvious effect on how people commute - whereas in European cities, a significant proportion of the population can live centrally in mixed-use buildings and be close to their work/leisure, in the UK/London the population generally has to get from one area to the other.
In terms of vehicles, buses and the tube/underground are the defining features, and any new vehicles you create should be in these categories. The River Thames is so well bridged that boats/waterbuses have not played a significant role for a looooong time. Afaik, the only realistic heliport would be at London City airport, east of Canary Wharf. There are no trams, except a one-off scheme in Croydon (south London). I agree with the previous suggestion(s) to replace the tram option with the DLR (Docklands Light Railway - serves the east of the city including Olympic sites at Stratford, and the commercial centre of Canary Wharf).
Using the largest map option (like Tokyo?) would allow you to include the major airport of Heathrow out to the west (by using a bit of artistic licence), with the eastern edge hopefully including Canary Wharf, London City airport, and Greenwich. This would provide some good opportunities for moving people, as the wealthy businesspeople working in Canary Wharf (east) and the City of London (central) would tend to live in wealthy residential areas in the west end, and select areas in north London. Heathrow out to the west would need to be the origin/destination of *lots* of people, and don't forget the main line rail terminals. Unlike other cities with one or two central terminii going through the city, London's railway terminals were built on the edges of 19th century London by separate railway companies, and don't go through London itself, or connect with each other. And there are lots of them - Kings Cross, St Pancras, Euston, Paddington, Liverpool Street, Victoria, and Waterloo are the biggest terminii.
Hope that helps...