I guess for non-translated town names, we all tend to use our own first language phonetics, or improvise on what we think could be appropriate.
But since we’re talking of the UK, here…I believe you can’t ignore the fact that there’s no way to guess how to pronounce names of towns in English - cause they’re totally random!
Therefore we (foreigners) pronounce many of them wrong - unless we happen to visit them or have some connection to that place.
Does anybody really worry about it, over there?
And if you think about it, with Welsh a few sounds may be a a bit complicated to get right, but at least phonetics is consistent!