Like purpledahlia said, you can work towards an NVQ while working in a nursery as a trainee, meaning you'll start building up valuable experience. What kind of age range would you like to work with? The work you do will partly depend on the age group, but it certainly wouldn't be sitting around all day, LOL! You would be involved in supporting children's learning, through spontaneous opportunities and helping to implement planning and 'focussed' activities. Maintaining a safe environment is important, so you need to be aware of what's going on all around even when you are focussing on a small group in one area of the room. And obviously building trusting relationships with the children and families is vital. Other responsibilities might include preparing food/supervising mealtimes, nappy changing/toileting, setting up/tidying away activities, paperwork... the list is endless, sorry for the rambling post, but I hope this helps!!!
Tip: Get yourself familiar with the principles of the curriculum... in an interview it's highly likely (even for a trainee position) that they'd ask about your awareness of this.