Leaking from base of tap - where do I start?

Elddis 540 Anvante 2006 - When any tap in the caravan is turned on the kitchen tap leaks water from the base of the tap - water doesnt make it through the tap at all - burst pipe, knackered valve, dodgy tap where do I start and do I really have to dismantle the entire kichen unit surface to access the problem - Please help away in 5 weeks and really would like onboard water this year

Teresa, Aberdeen
June 2010