So English speakers would tend to just pronounce the
letters as they would be in an English word, as far as possible,
perhaps ignoring the diaresis over the 'o'.
Sadly LN - you had better believe it - English was not my first Language indeed,
but when you see so many Modern English People making "cringe-worthy"
pronunciations of other languages, if you want an example then go to Wales in the
summer and listen to the "tourists" pronouncing the Welsh names, I have had many
unfortunate experiences with my Step-father (Welsh-man) on holiday in the
Principality, hearing the villainously bad way they say Dolgellau  (Dolgellow) with no
attempt at the "ll" correctly. If this be so - as I believe then the last thing they will
take notice of is the two "little dot-things" over an รถ 

(Actually the normal name in English is 'Valhalla', which corresponds
to the Icelandic genitive plural. I'm not really sure why that became
traditional in English. Perhaps it came via translations of Old Norse
texts into Latin?)
That is very likely so - for the Romans were worse by a damned sight - than
the English for putting their pronunciation on things, only thing they did  well
was to classify and subclassify the plants and animals and give then Latin
names, they are well done - but being half Italian I admit to a certain bias.