Just some general notes... I suggest you call the winery directly and make a reservation. I'm sure any winery would be happy to organise a tasting for you which doesn't include a full tour of their facility. If you just show up and expect a wine tasting then they might accommodate you, and I'm sure lots of people do it this way, but I personally prefer to avoid being given a generic hokey tourist experience and reserving ahead of time is always appreciated.
We had the best results when we said "I'd like to buy some wine, can I please organise a tasting for x number of people" - If you're not interested in actually buying bottles/cases then this doesn't work of course, and I totally accept that you may want a more casual wine tasting experience, but when we went in with the explicit intent of buying their wine, we found they were really happy to go further to accommodate us. Especially if they are a smaller operation relying on their wine sales rather than catering to tour vans. The owner of one winery happily drove us 3km back to where we were staying. Sorry I don't know that region specifically so I'll let someone else chime in with vineyard recommendations.
