There is a handy list of spacers to fit the coupe on the H&R website...
http://www.h-r.com/Click on the union jack for english text go to products then wheel spacers the on the right side of the screen search for fiat and it will give you all the spacers for all models here's whats listed for the Coop...
H&R name their spacers after the total axle displacement so a "DRA-System 40 mm" spacer is 20mm thick.
40145801 Fiat Coupé Typ FA/175
wheel number of holes 4, except version with self levelling DRA-System 40 mm 98/4, 58, 0 mm, offset: +1, 5 Approval
24145802 Fiat Coupé Typ FA/175
wheel number of holes 4, except version with self levelling DR-System 24 mm 98/4, 58, 0 mm note 3, 18b, offset: +1, 5 Approval
6014580 Fiat Coupé Typ FA/175
wheel number of holes 4, except version with self levelling DRA-System 60 mm 98/4, 58, 0 mm, offset: +1, 5 Approval
20145802 Fiat Coupé Typ FA/175
wheel number of holes 4, except version with self levelling DR-System 20 mm 98/4, 58, 0 mm note 3, 18b, offset: +1, 5 Approval
5014580 Fiat Coupé Typ FA/175
wheel number of holes 4, except version with self levelling DRA-System 50 mm 98/4, 58, 0 mm, offset: +1, 5 Approval
4014580 Fiat Coupé Typ FA/175
wheel number of holes 4, except version with self levelling DR-System 40 mm 98/4, 58, 0 mm note 3, offset: +1, 5 Approval
3014580 Fiat Coupé Typ FA/175
wheel number of holes 4, except version with self levelling DR-System 30 mm 98/4, 58, 0 mm note 3, offset: +1, 5 Approval
1014580 Fiat Coupé Typ FA/175
wheel number of holes 4, except version with self levelling DR-System 10 mm 98/4, 58, 0 mm note 3, offset: +1, 5 Approval