Since practice balls are two piece and they are "bat breaker" so I will recommend you a cheap bat (unless budget is not an issue for you and you don't mind forking out 300 quids or more for a net bat then it is a different story altogether).
Personally I would recommend low end Gray Nicolls bat. Why I said Gray Nicolls is because of the fact that they are hard pressed so they will work well against practice balls ala hard 2 piece balls. Apart from balls being hard the indoor surface is also hard and the ball skids which increases the impact on the bat due to greater speed.
As fan "jan" goes I would say this is very common phrase used when a Pakistani looks for a bat

. For that I would say it mainly depends how well you time the ball. Apart from timing I would say it depends on bats ping, in order to get best ping you have to spend time with the bat and knock it well.
Sweetspot position varies from bat to bat so in order to get a bat that would go well for you we should know your playing style.
Before you ask I didn't say Pakistan or any Asian bat because they are soft pressed and two piece ball can break them, however, being soft pressed bats they will ping very well in the beginning but as time goes the ping will start to deteriorate.
If you have any question(s) please don't hesitate to ask.