Ok I have answered my own question.
Working from having a 2D Polyline.
1, First off this Polyline needs to be in one continuous section so take your Polyline and merge it into 1 Line
2, Use the 3D Analyst tool called "Interpolate Shape" on your merged line
3, You can make a graphy from this but I would export out the newly created line because its just a graphic and not a real line after the Interpolate Shape tool has spat it out.
4, Then select this line and use the Profile Graphy button in the 3D Analyst tool Bar.
The only thing I can not work out now is how to export this graphy as an excel file as I keep getting a message "Cannot create file"C:TeeChart.xls". Access is denied.
Anyone know how to export the graphy to excel?