I recently done an oil change on my Audi A4 Avant 1.9tdi. At the time I didn't have the tool to open the oil filter so i couldn't change it. I've bought the took and am going to put a new oil filter in (2 weeks later). My question is, do it need to change the oil again or is it ok to just change the oil filter? A mechanic said I have to change the oil also as it could be contaminated with debris from the old oil filter.
When you change your oil, you never get all of the old out. There will be some left in the sump and on all the internal surfaces. Not changing the filter just means there will be a little more old oil left than normal.
Change the filter now as you suggested. If you want to you could change the oil and filter a week or so earlier next time.
Just be careful about where it's placed. The usual position on the side of the engine means that, at the very least, you'll want to have parked it overnight and let everything cool and settle first, and still put a catch tray underneath just-in-case. If it's lower down, it might be prudent to empty all the oil out into a clean tray (5 litre capacity minimum) before hand, swap the filter, then pour it back in. Otherwise you could have a huge mess and a lot of wasted oil on your hands, and end up putting half as much clean stuff back in anyway.