Heres some pictures of mine on standard Citroen setup if its any help.
Check about because you can get good suspension packages with good brand names with a drop as little as 25mm which probally would be better than refitting standard Citroen parts.
You wont really be able to do the rear yourself as Saxo's have 'Torsion Bars' at the rear which are in place of springs. Post where you are and people in that area might be able to point you in the direction of a good place to have the rear sorted
If you have a picture of the car then we maybe able to tell you how low its been dropped - 40mm, 50mm, 60mm etc.