Your dog might enjoy an active social life and might still be learning to fit in, whether it is because he/she needs to shape the training you have put in place, or perhaps it is because he/she gets extremely enthusiastic to the prospect of new experiences in the day-to-days scenarios.
You should remember that enabling your dog to participate in social and entertaining activities creates an enriched environment for him/her to blossom, enabling him/her to appreciate when he/she can relax and look up at you for guidance. So if you feel that he/she is enjoying the experience and that he/she is behaving well enough to take the trip to the high street and perhaps sip on a gorgeous cappuccino, enjoy.
There are a variety of café places and selected restaurants, hotels, attractions, and generally public spaces where both your dog and yourself can access great facilities. Sometimes they will even provide a bowl of fresh water for him/her which will keep him/her satisfied.
The need to avoid situations should be justified, for example if he/she is far too anxious or perhaps aggressive or reactive to certain situations. In which case it is important to build up reassurance towards your dog rather than inflicting a situation.
Finally always remember to ask and respect the policy of the premises you are visiting when it is unclear because it is their judgement and previous business experience that dictate their preference towards your dog, regardless small or big, that you will need to kindly accept. They probably still make a great cappuccino worth coming back for.