I normally hate it when someone replies to a question with "Why don't Google it?". Just for once, though, I'm going to suggest exactly that. My reason is that I've just tried this search string:
tour seville jerez bodegas
That resulted in lots of possible links. Many of them seem to be for very expensive private-chauffeured tours, such as this one:
http://www.cellartours.com/spain/wine-tours/se ville-tasting.html
(275 euros per person, falling to 195 euros per person for 6 people).
I did find one coach tour to Jerez but it only operates once per week and doesn't visit any bodegas. However, rather than me giving you loads of useless links it seems better to suggest that you do your own Googling.
If you can't find anything suitable from Seville, there will almost certainly be tours operating from central Jerez. Seville and Jerez are linked by a direct rail service. Although the trains aren't very frequent, you should be able to find some suitable times here:
http://horarios.renfe.es/hir/ingles.html
For example, the daily 0900 Andalucia Express (on the current timetable) arrives in Jerez at 1006. The fare is just 6.25 euros each way.
I aplogise that this doesn't fully answer your question but I hope that it points you in the right direction.
Chris