For any childcare situation, you need to trust your care provider. This applies for nurseries, pre-schools, childminders, nannies, babysitters, etc. If you don't trust your childcare provider... it's time to change provider.
You can never be sure what is happening when you can't see. Thus trust is vital. Many providers have an 'open door' policy, whereby as a parent you can collect your child early, thus see how things are when you are not 'expected'. However, practicalities can get in the way, as childminders are not at home all the time - they take/collect children from school/pre-school, they go on outings. So if you do turn up unexpected, and CM is not at home, then don't be alarmed - the children may be having a great time at the park.
With babies - childcare providers do daily diarys that help you get a feel for how your baby has been that day.
Childcare providers know that first-timers are anxious about leaving their precious bundle of joy, so don't feel that you can't ask them things part-way through the day. However, try to avoid constantly worrying and calling up every 10-15 minutes, as then both you and your CM are on tender hooks all day.
If you find that you can't face being away from your baby for your working hours, then consider other work - as long term, you need to be happy and your baby needs to be happy.