Westcarr joined Conference National club Cambridge United on a short-term contract in September 2005 after impressing during a trial period. He scored eight goals in 34 matches in the 2005–06 season as Rob Newman's "U's" posted a 12th-place finish. He chose to leave the Abbey Stadium in May 2006 after rejecting the offer of a permanent contract. Westcarr signed with Conference North club Kettering Town in May 2006. The "Poppies" finished the 2006–07 campaign in second place, but were denied promotion after losing to Farsley Celtic in the play-off semi-finals. He was moved out to the wing by manager Mark Cooper for the 2007–08 season, and helped the club to win promotion as divisional champions. In May 2008 Kettering reported Conference Premier side Stevenage Borough to the Football Association and Conference for allegedly making an illegal approach to Westcarr. He featured during pre-season for Stevenage, before he returned to Kettering for the start of the new campaign. Westcarr scored twice in the FA Cup Fourth Round against Premier League side Fulham as Kettering twice pulled level before losing 4–2. He was named as the Conference North's Player of the Month for March 2008. He ended the 2008–09 season with eight goals in 45 games, but was released by Kettering in May 2009. Westcarr joined Ian McParland's League Two side Notts County in May 2009. Off the pitch the club became unstable, as McParland was replaced by Hans Backe and then Steve Cotterill as an unknown investment company took control of the club. On the pitch Westcarr remained a mainstay as the club won promotion as league champions. He scored 11 goals in 50 games, including a hat-trick against Hereford United in a 5–0 win at Meadow Lane on 27 February. He signed a new two-year deal with the "Magpies" in June 2010. He continued to be a key player for the club under three more different manager – Craig Short, Paul Ince and Martin Allen – in the 2010–11 season, scoring 12 goals in 41 League One games for County. On 8 January 2011, he scored the opening goal past Premier League side Sunderland in an FA Cup giant-killing victory at the Stadium of Light. Westcarr signed a two-year contract with John Sheridan's Chesterfield in August 2011 after moving for an undisclosed fee (reported as £70,000). He hit 11 goals in 43 appearances for the "Spireties" in the 2011–12 season as the club were relegated out of League One.