Happened to Mr Movingin07 last year. Also an aussie passport - they just don't survive the wash! He had to fill in the forms but it took a week or so to get a new one I think - no hassle just took time (but he didn't try to get it faster because he has a UK passport too so it wasnt such a drama). Also no hassle with immigration - just explained the situation and got the work visa put in the new passport.