Then in the Norwich Under 14 squad, Seb Muddel was called up in February 2003, along with teammate Andrew Howell, to attend England international trials at Lilleshall. Whilst with Norwich's Under-16 squad, he played twice for the Under-19s during 2003/4 and has appeared for the Under-18s during 2004/5. In January 2005, he was offered a scholarship with the Canaries that commenced at the beginning of the 2005/6 season.

Seb was not awarded a professional contract with Norwich at the end of his scholarship in May 2007. He trialled with Bournemouth in May 2007

He joined Garforth Town in the summer of 2007. Garforth are owned by Simon Clifford whose Brazilian Soccer Schools, Seb attended.

After a short spell back in Norfolk with Dereham Town, Seb joined Norwich United in the summer of 2008. In the autumn of that year, Seb signed for rivals Wroxham

In the summer of 2011, he signed for Anglian Combination side Sherringham.