Whose Voice is it Anyway?

In the last couple of weeks I have come across an interesting conundrum. Part of my novel is set in another era which suits my own voice. The remainder is set in the 1990's and told from the point of view of a character who is nothing like me. That's part of writing, I hear you cry; convincingly taking on various voices but always with your own style. The problem is I keep imaging an agent (I never dare to imagine getting as far as publisher) reading my MS and thinking badly of the vocabulary etc, i.e. that it is not very advanced. I am comforting myself with the fact that I have concentrated on getting the story down, focussing on pace and particularly dialogue and not on description. Hopefully I will feel better when I edit and can add to the latter.