A former Football League defender with Middlesbrough, Crystal Palace and Preston North End, Harrison's playing career came to an abrupt end at the age of 24 when he sustained a double compound leg fracture.
"Full-time football is a massive lure for me, I've been a professional footballer for six or seven years previously, so to get back into full-time football in a club like this is brilliant, Harrison said.
"It was the main attraction, you are in a priviliged position to be a professional footballer and earn a living from it and it's something that's in my blood.
"Obviously I finished my career early and I've got a burning desire to go and finish what I probably should have as a player as a manager/coach.
"This will only be a stepping stone to greater things if I do a very good job, if I'm not doing a good job I'm not going to go any higher.
"If I am doing a good job then it's a 'two win' situation, the club are doing well and I'm doing well and we'll see what happens from there.
"Another massive attraction is that TNS play very attractive football which is something I tried to imitate when I was at Airbus - TNS were almost the model of where we wanted to be in the standard of football, and they have also got very good players."
Looking to the second half of the season Harrison outlined his targets.
"For a club of this size, we'll be going into every single game trying to win the league, full stop, that's the aim for the players and staff from top to bottom."