Dishwasher salmon is fine. Make it your main course for everyone. If you’re worried, make it this weekend for yourself!
In fact, that should be a rule of cooking.
Never experiment with your guests: Give them something that you’ve already made yourself.
Rule 2 would be lying about it 
As for menus, lessee. You’re serving for Australians used to BBQs. Sounds like my own relatives down under–
I’d whip up a basic green salad-- maybe throw in whatever citrus fruit is in season – although it’s as cold as it gets in Oz right now.
You can slice that up the day before if you really need to, as long as you wrap everything up airtight in plastic and stuff it in your fridge. But if you’ve got less than 8 people for dinner, even the most amateur chef should be able to slice and dice their way through 2 heads of lettuce and some veggies.
Go for some mashed potatoes-- You can easily do this the night before, and just microwave 'em for the day off. It’s also faster than baking potatoes, or doing something intricate with pasta.
You’ll want at least two veg-- glazed carrots are pretty quick.
Slice them (into sticks, not medallions) the day before, then night of yer dinner throw a copious amount of butter in a pan-- melt it-- then throw in an equal amount of brown sugar. Add a tsp of mustard powder-- then about 150 mL of wine or cider-- then add carrots. Let cook, stirring occasionally, for about 10 minutes, until carrots are soft.
Don’t forget bread-- pick up some nice buns during your lunch hour. If you want to dazzle 'em, make some herbed butter. Dill butter would probably be very good with the salmon, if you like dill as much as I do.
Is this your first time hosting a “real” dinner party?
Oh, and don’t worry if something goes wrong-- the very first time I had my folks over at my own place, I burnt the glaze on a ham. Some time with a knife fixed that one up fine…
