[1] Born in Caerphilly, Thomas began his career at Swansea City, where his prolific goalscoring record in the club's reserve side saw him handed his league debut at the end of the 1994–95 season against Plymouth Argyle.
Following his debut, he was unable to hold down a regular first team spot and was offered a move away from the club but instead chose to remain at Vetch Field and attempt to force his way into the side.
He scored four times during his first season at Ninian Park and pledged to improve his fitness during the off-season but only managed one goal during the next year, in a 1–1 draw with Oldham Athletic in October 1999, after appearing in just eight games.
[7] Following a formal disciplinary hearing, Thomas was fined the maximum amount allowed by the club which was believed to be two weeks wages,[8] but was not charged with any criminal offence.
He pleaded guilty to one count of threatening and violent behaviour and was sentenced to sixty days in jail as well as a ban from all football grounds in England and Wales for six years.