The following websites will help you find information on the River Thames in London, boats for hire and private charter:
River Thames:
http://en.wikipedia.org/wiki/River_Thames#External_links
http://www.portoflondon.co.uk
http://www.tfl.gov.uk
London Speed Boats:
http://www.londonspeedboats.co.uk/
http://www.thamesspeedboats.co.uk/
http://www.thamesspeedboathire.co.uk/
http://www.londonjetboats.co.uk/
http://www.thamesjetboats.co.uk/
London Party Boats:
http://www.londonpartyboat.co.uk/
http://www.partyboatlondon.co.uk/
Thames Boat Hire:
http://www.boathirelondon.co.uk/
Marine Filming:
http://www.filmlondon.org.uk
http://www.livettslaunches.co.uk/page/2.55.html
http://www.divingservicesuk.com
http://www.theknowledgeonline.com
Please let me know any more I can add to this list.