I searched the Procedures and Formalities section on the Market Access Database (http://madb.europa.eu/) for you. It is a good website which tells you about import duties and any special paperwork needed when sending goods outside the EU. I choose Israel and searched on "Shampoo".
This did indeed show a requirement for a GMP (Good Manufacturing Practice) certificate to clear customs. It also gave contact details for the responsible body for pharmaceutical products and cosmetics - the Ministry of Health, Pharmaceutical Administration, 29 Rivka Street, P.O. Box 1176, IL-91010 Jerusalem, phone numbers: +972 2 5681200, 5681392, 5681352, fax numbers: +972 2 6725820, 6725827
You (or perhaps your customer in Israel) should contact them first - detailing the product (ingredients, cosmetic or medicinal aspects etc) and confirm that a GMP certificate really will be required to enter the country.
IF a GMP certificate is needed you should contact MHRA (Medicines and Healthcare products Regulatory Agency) here in the UK. They do inspections and provide certificates. I'd contact the Borderlines Team in the first instance 020 3080 6759. (Borderline team determines whether a product is medicinal or not).
Lastly, the MHRA inspections needed to gain a GMP certificate can be costly (£thousands not hundreds). There can be financial help with the preparation work needed to pass an inspection and the Manufacturing Advisory Service are your first port of call regards that. See this webpage in relation to that -
Export Development Adviser,
UKTI East Midlands
0845 052 4001