Hey Googe,
I would suggest you proceed with caution, essential oils may be toxic if ingested orally, many must be diluted with a lighter non scented ( flavoured? ) oil prior to being applied to your skin.
I just had a read of this.
http://en.wikipedia.org/wiki/Essential_oilBased on what I read, I personally would not try it, but given your missus has a background with the stuff that is a plus.
My thoughts are there is a big difference in say macerating some lavender flowers in a bottle of nice neutral compared to adding a concentrated oil of lavender from a bottle, lavender oil might be made from the whole plant and not just the flowers, the taste might be sour or bitter even though it might smell good.
I'm not trying to scaremonger or anything, I would just suggest you be careful if you try it.
Cheers
GTH