Cheers guys, cracked it.
Any idea how u do it on a windows based laptop?
Start off by going: start-[all] programs-accessories-system tools-character map. You can select the character here. But it's slow.
At the bottom of the window, it gives you the Unicode character code, and the ALT-code. On an extended keyboard, you would press and hold the 'ALT' key, while typing the numbers on the numeric pad. Not certain if that works for a laptop without the extended keyboard. Perhaps if you switch on 'Num Lock'?
So, to type a Swedish Å (that's a capital A with a ring above it, you would hold an alt key, and type '0197' on the numeric pad.
Much simpler on the Mac... That same character is shift-option-A. For other diacriticals, say, the umlaut (two dots over the letter), you simply type [Shift-]Option-U, then the letter you want. Works with A, O, U...
Almost forgot - you can always turn on a different keyboard map. For Swedish, that would turn your {,} & | into the three extra letters English doesn't have.
Good luck!