Go for it Mum2Princess! I will agree with most of the other posters: tinted moisturiser, a touch of powder, mascara and lip gloss are all you need to look neat and professional. A classic pair of earrings also make you look more professional I think.

My other tip would be to make sure your nails are neat - I don't use polish but do make sure they are trimmed/filed and maybe buffed a bit so they are shiny.

All the best for the new job! Remember to relax and smile - it's not that hard! : )