Isn't the idea of the exercise meant to challenge you to think about this potential demographic for yourself?

I don't mean for that to come across as rude! But if you're serious about developing these key skills, I think you should spend some time thinking about the various customer profiles and completing the task itself. It sounds like you want to use this task to re-design a website for the given profiles? If so, that's a completely different task. I think you should focus primarily on what it asks you to do.

The task is asking you to consider all of the different factors at hand and how they could influence the customer profiles. Here's what comes to mind for me;

• It's a small town coffee shop. Well as it's a town, I would expect a completely different demographic than that of a city. What do you think are the main difference between a city and a small town? What kinds of people live in these environments and how does this impact their day-to-day lifestyle? For example, I imagine city folk work within the city, whereas a town, people will be travelling outwards to their jobs. So who does that leave to visit this coffee shop during 9-5?
• What environmental factors might influence the demographic? Does the town have a number of retirement homes? What about local schools? Right there, you would consider elderly people and stay-at-home parents as potential customers. So why would they visit this particular coffee shop? Nowhere else for them to go/close by? How about if this town had a college? Would many students go there during their lunch hour? Why? Maybe they have great tasting coffee, maybe it's just cheap and convenient?
• Which leads to the next point, what about the coffee shop? What sort of interior design does it have? Would it attract a trendy crowd? Does it feel welcoming? What are the prices like? Who owns it? If it's a small, family run business, that has a certain appeal of itself. You would imagine a family run should would look very different to a shop owned by a young businessman. I imagine a local businessman might create a coffee shop that looked more like a bar, whereas that family run shop - perhaps the coffee making process is kept for the kitchen as it reduces the noise pollution? Do you see how this can impact the customers it would attract? However, you would imagine the shop is designed to suit the town and demographic!

There are so many questions to consider and all of these have an impact on the customer profiles! You should create a make-believe town or look at one near you and just have fun thinking about all of this, creating profiles for at least 3 types of demographics. See where it takes you!

Because if I have learned one thing doing copywriting, it is that understand customers, behaviours and general psychology will get you a lot further than studying existing ads/work. If you don't have this background knowledge/skill, how can you appreciate the method that went into the creation of the copy? Copywriting is fundamentally a people business.