Sounds like you are confident enough about the 'driving' aspect, just the manoeuvres (all of which involve reversing) which you don't have the confidence with.
My suggestion would be to get a family member or friend to drive you to a supermarket carpark outside of shopping hours (trust me, when they are open those things can be a far more intimidating driving experience than normal roads). Plenty of space, lack of other cars, and handily painted lines for you to practice. An added bonus* is that as it is not public roads, you don't need to be insured on the car to drive there.
*disclaimer to the effect that this may be an incorrect assumption on my part, and I take no responsibility etc etc...