hi mummy17,
may I suggest that you don't talk about the "couple of weaknesses" that you spotted although you have very good intentions :-)
From my experience, people who have been very honest during interview (both phd AND job) and have spoken about "weaknesses" have lower chances of securing the phd (or job). I am one of them. I have since learnt from that mistake.
Now my perogative is not being dishonest--but rather do not say anything that will put me in a bad light--in other words--say something positive OR keep my mouth shut :-)
So maybe you should highlight more what your research will find, and what benefit it will have. Remember to post back and let us know how you did :-)
best of luck :-)
love satchi