Whilst it may not be common practice, there may be churches that let members of the public climb the tower or visit other high-level parts of their premises.
If you choose to do this make sure you carry out a risk assessment to decide the maximum number of people on a tower tour at any time. To do this you might want to take into account the size of the tower, number of staff and means of safe evacuation.
Think: Will this change in different weather conditions? Consider the appropriate number of staff and volunteers and consider the circumstances of those on the tour and any requirements those persons may need, in order to establish how many persons can safely go up the tower. You may need to set the figure differently according to the circumstances.