Talk to your Ringing Master or Tower Captain – find out whether they’d be happy for you to run an occasional practice. They might be very grateful for the offer – after all, it can be hard work running every practice week in, week out and if there’s someone else in the tower who can do it occasionally, it takes the pressure off a little. If they’re not happy for you to run a whole practice to begin with, perhaps just planning then running the first half of it would be possible.
If they are not willing to let you run a practice in your own tower, consider approaching your local Branch or Guild Ringing Master to find out whether they’d be happy for you to run a branch practice, or whether you could contribute by running a specific focused session on a particular skill – such as learning to Plain Hunt, calling Call Changes, calling touches or developing foundation skills, whatever is helpful to your local area.
It’s also straightforward to ‘borrow’ a tower for a session and run a mini workshop on a particular topic, invite local ringers who would like to take part (and helpers of course!)