You need two of the following:
a) 100 hours of instruction during the validity period of your rating, of which 30 must be in the 12 months before expiry.
b) seminar
c) flight test
So I guess of you haven't instructed since 2001 you're stuck with b) and c)
To remove the restriction from your rating i.e. to become a FI not FI(R) you need 100 hours of instruction and to supervise at least 25 student solo flights, plus the recommendation of your supervising FI.
As BEagle says, get a copy of LASORS from the CAA. I am amazed that they are not charging £50 a copy as it seems far too good to be true (if anyone from the CAA is reading that is NOT a suggestion
)