I think the London Eye has now become just about the most popular London attraction for visitors. Certainly it’s in demand as an add-on to London theatre breaks but not everybody who has a short time in the city manages to get a flight that suite them without queueing for ages. The secret I’ve found, during an off season weekday, is to turn up around mid afternoon and buy a ticket for one hour later. Then wander around the south bank for a little while and come back and join the short queue for the London Eye flight. If you buy a theatre break though, you can get a fast track London Eye attraction for quite a reasonable fee and at a a time that suits.
The London Eye is on the south bank of the Thames, opposite Westminster so you can head for the Hoiuses of Parliament and then walk across the bridge, or else go to Waterloo Station and exit where the Eurostar trains used to come in.