Slabber was released by Stevenage on 17 May 2007, and signed for Conference South club Havant & Waterlooville two months later, ahead of Conference National side Halifax Town. He also had an unsuccessful trial at Rushden & Diamonds in July 2007. He scored his first Havant goal against newly formed Hayes & Yeading United, a game that Havant won 4–1. He was released from Havant & Waterlooville in October 2008 having made 29 appearances, scoring twice in the Conference South, before re-joining Grays Athletic.