There are four quadrant photodiodes made specifically for this purpose. You can use one of them.
If the laser beam is frequency modulated, you can easily detect the laser signal even if it is not visually seen. After a couple of meters, the beam will be visible to the photodiode even at a distance of 1 inch or so from the main beamline.
With a four quadrant detector you can also determine whether the beamline is on the left or right, top or bottom.
If you are having lots of ambient light, you will need a narrow band filter, perhaps interference filter corresponding to the laser wavelength.