Hi fellas, and ladies if there are any!

I need to replace my chain and sprockets and was wondering if anyone could recommend a good kit to go for? I thought I had to buy them seperate (if this is better please let me know?) but after searching the net I found kits which include it all.

Also, is there any tips for replacing the chain and sprockets? Especially the front sprocket, not looking forward to that

Can anyone recommend somewhere to get them online? preferably in aus, but definitely that ships to aus!

Cheers