Cappuccino or crappuccino in Cardiff?

I've been roped into a family outing to Cardiff, mainly because I'm the only one who knows how to get from A to B there. My trips to Cardiff are usually brief, solo ones. I normally have a specific place or purpose in mind, do what I need to do, and get out of there fast. Not that I dislike Cardiff, quite the opposite, but I'm not one of these people who can mill around shops for hours. The family outing will be different, an excruciating tour of every shop in the city centre. There will also be elderly persons in attendance, who demand a cuppa every half hour or so. Which brings me to the original purpose of this post.

Can anyone recommend somewhere cheap and cheerful for a cuppa and a bit of grub in central Cardiff? Fast food places are a no-no, as the oldies hate them [and so do I]. Similarly, sandwich bars, baguette places, fancy cuisine and establishments with zillions of neon signs and/or weird-shaped furniture, are also out. Suggestions, anyone? Oh, and the place must also be non-smoking, as I'd sooner eat my lunch in a public lavatory than be smoked over.

All suggestions gratefully received ....