I answered my own question again:
In my case I had the option of changing the coordinates slightly - I wasn't trying to find the coordinates of a fixed line, so this probably isn't much use to anyone.
Basically I made the distance of my line a whole number, by altering my x value slightly (I used Pythagoras' theorem to find the distance, then round it and then work out the new x value I would need to get this distance).
Once my distance was a whole number I used linspace to create a vector of x and y values between my points i.e. linspace(xvalue1,xvalue2,distance_between_them) and voila!, I have the coordinates I needed.