Hair Dye/ Highlights, first trimester?

I have heavy blonde highlights with my dark brown roots coming in.  I am just 4 weeks. Starting a new job in two weeks and want to look professional.
 Are foil lowlights at salon ok, since it's not on skin? I'd like to start getting some darker lowlights to "even out" my look so I won't have to be a highlighting addict anymore. I am considering an all-over natural henna dye.  
Any experience with any of this?