I work in a UK university, so you can believe me when I say the following....
The reason you're getting confused is probably that UK universities (perhaps with a small number of exceptions) don't operate a semester-based system. Each year consists of three terms which typically run roughly over:
October - December (Autumn or Michaelmas)
January - March (Spring or Lent)
April - June (Summer or Easter)
Exams of any real consequence take place during the end of the third term. So you might want to consider aiming for July rather than the end of any spring semester, although it depends a little on the university.
I've looked at the term dates for Kent and this year's are:
Autumn Term
25 September 2006 - 15 December 2006
Spring Term
8 January 2007 - 30 March 2007
Summer Term
30 April 2007 - 8 June 2007
so there's a one month break between the Spring and Summer terms but your friend may want to spend much of that time revising and preparing for examinations. Otherwise that might be an opportunity for you.
Failing that, any point after early June should work for you.
I hope that clears things up. The below link is to the term dates for Kent for the next decade.