Extract from Lasors should clear this up for you...
You remain FI(R) until ....
"The Supervisory Restriction can be removed on
the recommendation of the supervising FI(A)
once the applicant has at least 100 hours flight
instruction and, in addition, has supervised at
least 25 student solo flights.
It should be noted that supervision of a students
PPL(A) qualifying cross country flight is counted
as one flight only. Approval of first solo flights by
day or night and first solo navigation flights by day
or night are excluded."
There are further additions to the rating to allow you to instruct at night and instrument training.
Lasors contains all the info - section H.
Link here.
http://www.caa.co.uk/application.asp...detail&id=1591
All the best
Az