Does anyone know if there is a topical treatment available for Chicken Pox rash - obviously the virus isn't treatable as such, just the symptoms, but a pharmacist has told me that there is nothing available in France. Is there any equivalent to Calamine lotion out there or something similar???

Try asking a pharmacist for thisGel de calamine Therica; This is a proprietary calamine gel.

http://www.eurekasante.fr/medicaments/vidal-famille/medicament-bgelca01-GEL-DE-CALAMINE-THERICA.html
Here's the page for you.

Also, I found that a tablespoon of salt in the bathwater helped dry up the pustules

What your pharmacist probably meant is : there is nothing available over the counter.

In France most medicines are only available with a prescription, and pharmacists rarely recommend a product over the counter, unless it is inofensive (ie : useless), especially for children Call the doctor out he/she will prescribe the required medicine.

http://www.farmaline.fr/fr/chercher/+calamine%20+lotion/?gclid=CISLyNOn6a8CFcohfAod31wt0A
calamine lotion online

Pop along to your doctor and get an ordinance for the gel which is excellent, stops all itching .