I will leave the matter of tea to someone who is more equipped to answer it.
I have a different question! Which hopefully won't overlap too much with plot help.
How broad is the public library system in Britain? How about as of 1971?
I'm looking for a place that Lily and Snape might go as children in the winter time (so probably not playing out doors at least not all the time). The first thing that came to mind was a public library, but I'm not sure their industrial town would necessarily have one, much less one that is particularly accessible to two kids.