OSGB will only work for UK based locations surely. I missed where the questioner mentioned the country he wants to use, but I would have thought that UTM would be more likely to serve his purposes (assuming reasonably short distances are involved).

Update: I see that the original questioner has worked out the appropriate zone. For anyone else looking here let me explain what UTM is.

The US military needed a way to specify locations that would work wherever they operate (i.e. anywhere on the Earth). So what they did was split the world into 6 degree longitude slices and have a "Transverse Mercator" projection for each. So locations between -180 degrees and -174 degrees are in UTM Zone 1, -174 to -168 in Zone 2 and so on. New York, being at -74 is in Zone 18 (-78 to -72).

The other thing to notice is that there are different projections for locations North or South of the equator. So the final suggestion would be to use the zone "UTM18N"