I'm just working here in Hk. could it be possible for me to visit the great wall and can go back?

Arlene, do you mean that you want to visit the wall at weekends? I am afraid that two days journey between Beijing and Hong Kong can be done if you take plane. Round-trip air tickets costs at least CNY2000. Considering of other expenses, you may spend at least CNY2500 for a trip to the wall. If you really want to do it, I think you just choose to visit Badaling section. You can take bus no.877 from Deshengmen to the wall. It takes around 1.5 hours on the way.