...well! Quite a lot actually. I was struggling to find some names in Old English and decided to turn to the Old English Facebook page, and got a little help with one: Jerusalem.
Rebecca Katya Danicic wrote "hello! I just joined this group, so this comment's probably too late. However, i've just been translating 'The Wanderer' and came across the compound 'eardgeard'. The noun might mean 'city' and literally translates as 'homeland-dwelling', but it is used of Jerusalem in the triad of poems called 'Christ'."
I'm guessing this is a literary word, because Dr Stuart Lee, of Oxford University helped out here and let me know that Jerusalem was Ierusalem. How easy was that!
Normandy was Normandig, which when you know 'g' was pronounced 'y' makes sense.
The others, and a few extras I came across:
Strathclyde comes from the Celtic, Srath Chluaidh. But I found an Anglo Saxon Chronicle ref, involving beating up the men of Cumbra land
Flanders: comes from Dutch, I think,and I couldn't find a better word so I used Bruges, which was Bricge
Norway was Northweg, which means the North Way. I guess there must be a South Way somewhere....
I wanted the book to start in Viking Dublin, for a number of reasons, and finding old english names for Ulster, Connaught and Munster were quite difficult. I found a Norse name for Ulster, Ulfastir. Munster didn't really have an equivalent, but the roughly similar kingdom (which gives its name to the Meath of West Meath etc) was Mide.
Saxony: I thought would be tough, but the Old English had a fond feeling for the Saxons they left behind and (from Bede) is the name Eadlseaxum: the Old Saxons.
I really enjoyed the search, and during it I realised I've at last reached the stage of knowing enough old english to work these out, which also felt great.