Hi bm, and welcome !We live and ride in rural Iowa on hard surfaced roads and currently ride 10-20 miles each evening and 20-40 miles on the weekend. We are steadly increasing our distance and want to be ready to do local club rides yet this year ...
Does your local club have beginner rides, or 'get acquainted' rides, that sort of thing? Many clubs have short (20 miles or less), relatively slow-paced rides on their schedules, and it sounds like you and your husband could handle those just fine.
One of the many benefits of club rides is to see for yourself what kinds of bikes other people are riding, and you can ask questions about their bikes - what they like, what they don't like, what they would have done differently had they known what they know now, that sort of thing. Trust me, any biker worth her salt will looove to talk about her bike.
And, you can pick up bike shop recomendations too.
You didn't mention this, but just in case this is in the back of your mind ... don't worry that, just because it isn't a road bike, your current bike isn't the 'right kind' of bike to go on club rides. I see lots of hybrid and mountain bikes on club rides - in fact, a lot of women rode the Cinderella metric century last sping on hybrids and mtn bikes (whether they finished the ride, that I do not know).
As for how long to test ride ... that's a tough one, simply because, at least in my experience, in first going from a hybrid to a road bike, the position on the road bike was so different that everything felt weird to me at first. I guess that underscores the importance of having someone who knows what they're doing fit you properly in the first place! But even once you have a bike that's reasonably good-fitting, you will most likely need to tweak the adjustments - handlebar height, saddle height, saddle tilt, etc. - to dial-in the fit, and that could take a couple of weeks. Once you're accustomed to riding on a road bike you will know what works and what doesn't work for you. But that's what makes that first road bike purchase kind of tricky...
Oy, where am I going with this ... take as long as you need for the test ride, and as long as you are comfortable with. Once around the block sounds a bit short, although you're probably riding in an unfamiliar area, on an unfamiliar bike, gee no stress therebut if you're a little concerned about going out very far in an unfamiliar area, then just ride around the same block a few times - in both directions. Nothing to feel guilty about - they probably have your driver's license, so it's not like you're going to run off with the bike, and it's part of doing business for the shop, so don't sweat it - would an auto dealer expect you to only drive around the block when you're test driving a car?
OK, enough random babble from me, hope something in this helps...
- Jo.