mattsmummy,
i apologise first if i sound harsh.
I don't understand your worry. You said that you have not been a practising Catholic. So why do you worry about bringing up your son following the faith? it didn't bother you that you are not practising the faith already, so how is that for your son?
If you are not practising, then practically speaking, and realistically speaking, i think it will be very difficult to bring a child up in a Catholic fashion. Because the child's best teacher is his/her own parents. No amount of cathechism classes will do. And godparents can't help much either. If you don't practise the faith actively, how do you think your son will learn to live his life as a Catholic?
And as for the child's baptism, it is not a ceremony to make the child a member of the church. It is an OUTRIGHT expression of YOUR commitment as a parent to bring him up as a Catholic child.
From how i view it, it might be better for your son not being half-baked and half-nurtured. Unless of course if you yourself make a very strong commitment, and stick to it (!!), to start practising your Catholic faith.