Are you allowed to take your camera into the Abbey Charles? Some shots would be very acceptable here.

I searched for Cosmati Pavement in the Royal Collection and got only one result http://www.royalcollection.org.uk/press-release/royal-academy-celebrates-diamond-jubilee-with-gift-of-art-for-the-queen

The Royal Academy has twice given portfolios to the Queen. One was on her Coronation in 1953. The second was on her Diamond Jubilee and included a drawing of the Pavement.

Westminster Abbey link with quirky details -
http://www.westminster-abbey.org/our-history/art/cosmati-pavement

The Conservation link -
http://www.westminster-abbey.org/conservation