get a copy of "the book of bivvy"
gives you lots of useful info and some nice route/challenge suggestions. Also tells it like it is, without any bullsh**
It's funny how bivvying in suddenly becoming popular in the non mountainearing masses. To do it properly you want to be out for a least a week, that way you really learn how to travel light and be as self sufficient as possible.
definitely start with the odd night out though as you soon learn what's worth taking and what is excess weight.
hints:
thin light sleeping bag and a warm jacket is much better n more usable than a big sleeping bag.
down sleeping bags do not like bivvying in the wet or being fully zipped into a bag without decent ventilation as they get a bit soggy and turn to cack if you are not careful.
army ration 24hr packs are you friend as they are cheap, have enough food for a couple of days using minimal water and you can eat them cold if it's widdling down and you just need to zip up tight for the night.
Finally- Have a nice drink in a hipflask for a nightcap.
Have fun 😀