Based on my exploratory visit - yes you can enter the shop. It isn't as casual as stopping off at your local convenience market, but that is due to understandable security concerns (e.g. a receptionist checked my ID, presumably to verify my age - I'll be 70 next month - before buzzing me through a locked door into the sales area; there are people around, I'm sure, who are looking for justifications to generate paperwork hassles and even a shutdown, e.g. for failing to make a very careful age verification however unnecessary under the specific circumstances).
You are absolutely welcome in!
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