Piccadilly Market
Piccadilly Market at St James's Church Piccadilly is now a five-day-a-week lunchtime food market in the St James's district of the City of Westminster. Occupying the courtyard on the North side of St James's Church, Piccadilly. It is close to Piccadilly Circus, Fortnum & Mason and The Ritz London Hotel.

Piccadilly Market at St James's Church Piccadilly is now a five-day-a-week lunchtime food market in the St James's district of the City of Westminster. Occupying the courtyard on the North side of St James's Church, Piccadilly. It is close to Piccadilly Circus, Fortnum & Mason and The Ritz London Hotel.
Check the official site before travelling; hours and prices can change.
More markets

Borough Market
London's defining food market — go early Saturday, eat your way around the perimeter.

Columbia Road Flower Market
Sunday-only flower market in the East End — 8 a.m. for choice, 2 p.m. for prices.

Maltby Street Market
Borough's smaller, scruffier sibling — railway arches, weekend only.
Source: wiki-list