By george dwarves are british, i think

[The Squatter of Amon Rûdh]

That depends on which stage of conception we're talking about. The Dwarf-runes used in The Hobbit are unquestionably of the Anglo-Saxon type, and Tolkien confirms it:

There is the matter of the Runes. Those used by Thorin and Co., for special purposes, were comprised in an alphabet of thirty-two letters... similar to, but not identical, with the runes of Anglo-Saxon inscriptions.

Letter #25, to the editor of the Observer, printed 20 February 1938

Earlier he is less circumspect:

...except for the runes (Anglo-Saxon) and the dwarf-names (Icelandic), neither used with antiquarian accuracy, and both regretfully substituted to avoid abstruseness for the genuine alphabets and names of the mythology into which Mr Baggins intrudes - I am afraid my professional knowledge is not directly used.

Letter #15, remarks included with a letter to Allen and Unwin, 31 August 1937.

The Angerthas is Tolkien's own invention, although obviously inspired by the runes of the Futhark. Basically (and rather too simply) the Anglo-Saxon and Norse runes are descended from the same alphabet. There's more than one Scandinavian runic alphabet, but for an explanation of them all you need a runologist. There are plenty of rune sites on the web, but if it isn't a university you can't trust it.