Car headlights adjustment for Opel Zafira French car.?

I have a French Opel Zafira elegance 2002. I find the adhesive headlight adjusters,used when visiting the U.K. tend to fall off & are quite pricey at about €8 a pair. I've read online that I may be able to just adjust the headlights from inside the car.
Does anyone know if I can do this and if so how it's done? Many thanks in advance for advice.