With cab rides costing $100 US from Heathrow to your hotel, it is very wise to seek a bargain hotel in London.
In the City Center, lodgings might run up to $175 US per night. But hotels near the 1-milliion square foot ExCel Enhibition Centre in the Docklands area east of Canary Wharf on the Thames cost about half that when there isn’t a convention in town. The Ibis London Excel is just 50 pounds ($87 US) per room on weekends and about 60 pounds ($105) on weekdays.
For these savings, you’re just seven stops away from the Tower of London by subway or rail. As they say on the Underground, Mind The Gap.