Can anyone advice how reputed is the Nottingham Kaplan Law School in London?

It's part of Nottingham Trent (Nottingham Law School):
http://www.kaplan.com/AboutKaplan/PressReleases/Archive/2006/June-22-NottinghamLawSchool.htm

That's correct.

Nottingham Law School (in collaboration with Kaplan Law School) is one of the leading provider in the UK for postgraduate education (LLM, GDL, LPC, BVC), awarded an "excellenent" from the Bar Association each year.

In Germany it is ranked among the top 15 law schools:

http://www.azur-online.de/pic/2005_01_LLM-GB.pdf

http://www.anwaltsblatt-karriere.de/downloads/Heft1/LLM-Report.pdf