Bleaching My Henna'd Hair Blonde?

Tomorrow I have an appointment at the salon. So this is being done professionally.

I henna'd my hair about 4 months ago, and since then I used a medium ash brown color over it about two months ago. I bought some powder bleach and cream developer to do a couple streaks as a test. The hair came out a caramel blonde with some orange undertones. I did not use a toner. Do you think I will be able to (professionally) achieve a blonde color (almost an ombre effect from dishwater blonde to light honey blonde like this http://images5.fanpop.com/image/photos/31400000/ta... considering that it turned out light orangey caramel with a home bleach kit and no toner or purple shampoo? I am doing an oil treatment now to prepare my hair for some damage. But other than that, think it will work?