No time limit, so you're welcome to join whenever suits you.
For finding out more about the party, there's an excellent Facebook group for new members (there's a little incentive to join now :) ), this subreddit is pretty darn good too and you'll get local party contacts with your membership.
The Lib Dem Podcast is also excellent: https://www.buzzsprout.com/369719
You might also find some of my email lists useful: www.libdemnewswire.com
You maybe don't mean to be rude, but frankly you are whether you mean it or not. People don't deliver leaflets for fun, they put a lot of work and money in because it is the only way to deliver consistent election results, proven over years of very expensive wins and losses.
I am willing to bet that every single Liberal Democrat elected representative got where they are with heavily paper based campaigns. I am not aware of any that didn't. But if experience from experts isn't enough for you then buy this book: https://www.amazon.co.uk/Liberal-Democrats-Cornwall-Character-Campaigns/dp/1511428945/?tag=marpacsblo-21