Hi, the only way you can correctly set the headlamp aim is by using a headlamp aim and beam pattern tester, every mot station will have one so just pop along to your local mot place and ask them to set them up for you, shouldn't charge more than a half hour labour, This way you know they will be set within mot tolerances, however, I have known some aftermarket headlamps to come with the inside of the headlamp detatched from the adjusting mechanism.
In the meantime, just set them too low so at least you won't dazzle oncoming cars!