- What do they see you doing (main task
wise) in the first three months with
them?
Might be handy to know if you are an 'imposter'!
In all honesty, take care bluffing your way into a role that you will not be able to handle - all that may happen when you are 'found out' is that the company will terminate your employment, possibly on the grounds that you were dishonest during your interview, and this could really screw up your future chances elsewhere - especially when next asked "why were you only with x Company for three weeks?"
I appreciate your situation - I was made redundant a month ago (finishing end October) and it's not a great feeling to be facing unemployment (or to be unemployed) and during an interview I went to a couple weeks back I had to be honest and say that I was not 'up to date familiar' with a couple of the areas of the job description, but that I would get myself up to speed if I was employed by the company. The honesty paid off and I got the job.
Good luck.