Under or over i.e. between the towers, the span is 200 feet.
The Lancaster has a span of 102 feet.
Fly so the cockpit goes directly below the big badge and above the join on the bridge and you will have about 49 feet clear either side. There will be s slight error with regard to you're seating in the cockpit. Apart from that, simple.
If you can land it on a runway you can keep it within the towers of London Bridge.