Hi there,
Just to let you know, I create all my own artwork and have no problem with you, as a cardmaker, letting your imagination and creativity take over when designing your cards. If you only wish to use a part of the whole sheet that I have designed, then that's entirely up to you. If it has inspired you to make a particular card then GREAT! I, like so many other designers have said, am always astonished by the sort of cards that can end up coming out of my designs. So, for me anyway, go ahead and enjoy.
Lucy x