I need to build a online membership system that allows members to edit and change their particulars online or reserve places for activites that are being organised. Would the usage of servlets connecting to a database suffice?
Sure. This is a "bread-and-butter" servlet application. Depending on how complex your HTML is on the pages, you may want to also consider some sort of templating system such as WebMacro http://www.webmacro.org/ or JSP to generate your servlets from marked up HTML.