You shouldn't have a problem with the credit card. With the bank account you just need to declare the interest and the tax already paid (to the UK). remember UK account deduct the tax automatically.

Hi,
I've been doing my and OH's tax returns for the last 3 years online and it is so easy. Unless you are studying aswell as working or a nurse then it is simple.
All the questions asked online make it easy to do. I have claimed for course fees, mobile phone costs, electricity, books, dependent spouse etc and had no problems. This year I'm a full time student so it will be easier. Salary packaging is also simple to include and once you get the group certificate (earnings and tax) you can just enter the numbers. I think you have to earn over $50,000 to actually have to pay medicare levy so you get some money back for that aswell.
With the online system, all you need to do is download the program, enter all your numbers, and see if you are happy with the results. You don't need to actually submit it. So, try it out, see if you can understand it, see if you are happy with the recommended rebate, and if you are, then you can enter it, and the money arrives in your account within 2 weeks. Also, from what I understand, most employers pay more tax for you than they need so you should get some money back regardless.
(please correct if I'm wrong as I've had afew drinks tonight )

Hope this helps

Sass