It’s as difficult as you want to make it. I fly every other month with my just (birthdays last week) 2 and 4 year old on my own.
All rules go out the window so they have a treat only on a Saturday normally and no tv in the week. Flight days that goes out of the window if they are good on the plane they are allowed to choose some chocolate and watch the ipad (with earphones please dont inflict the noise on other travellers) which they love.
Sorry ive not rtft but my Main advice is:
Take change of clothes for each child and you.
Double nappy any of them still in nappies so you just take off the underneath nappy when changing in seat.
Book a seat for toddlers.
Can even double nappy pull ups is 23 month old not potty trained. Only need to change a poo then.
Suck a bottle on take off and landing.
Get a ruck sack bag with passport size compartment at front keep all documents here.
Take food and snacks that are not too messy. Ham wraps, cheese, bananas grapes etc.
Babyzen yoyo or similar is the best buggy as folds to hand luggage. Both mine can get on it in airport.
Dont board first the less time they are on the plane the better!
Never book a flight that is rubbish times for the kids. Overtired hungry children make terrible air passengers!
Layer t shirts long or short sleeved (planes are cold it never fails to escape me how people traveling with small children in shorts and t shirt are not aware of this) and remove as necessary if get dirty.
Most importantly remember it’s only a few hours of your life so dont worry about it just deal with things as they happen!