sulpak,
Welcome to THR.
I do not know your laws so please forgive me. You "get it" because unlike some around here, you live in a whole different setting! There are some members here, that DO have experiences in Settings like yours, and have been shot, and have shot back and killed in Civil Unrest.
Yeah, I get a bit fed up with NetNinjas on forums - and I don't apologize for it.
Dang! First you need someone you can trust to give you the run down on Firearm laws and Legal matters in defending yourself. Second, you need some training in regard to these Rebels - Id'ing them, how they operate, strategy and tactics they use ( and I mean S&T as defined as it is supposed to mean, not NetNinja-Speak).
Personally, I suggest a Pump, for the simple fact ( I hope) it is more readily available and less monies for you. Pumps are not ammo dependent as some semis are, so not knowing if your ammo choices are as good and varied as we folks in the US, the pump will feed ammo choices better.
A simple, used, 870 with 2 3/4" chambers will work great! Yes, you need some choke on the shorter barrel. Meaning, if you find a good used gun with a 26" fixed choke ( no screw in choke tubes) - get it and do not whack the barrel...that choke is important! Later on, you can find a shorter barrel.
Monies are best spent on training and ammo, - not gadgets. About all a defensive guns needs is to fit shooter, have good solid beads, a sling, and perhaps a light. Forget this other crap, funky stocks and all.
Stick with plain ammo, that tests according to pattern boards work best in your gun, and plentiful. 2 3/4" shells are all you need, and different brands of 9 pellet 00 buck and simple lead slugs - are all you need. Just let the pattern board reveal what your gun, and loads do best with, and then stock up on those. Use the lightest target load, to practice and ingrain basic concepts.
You really need the wisdom and training of Louis Awerbuck. He has BTDT and is a Great Trainer - he would be ideal for you. Heck, I would write Awerbuck, and ask for his best suggestions and get the tapes and books he suggests.
http://www.yfainc.com/
YAVAPAI FIREARMS ACADEMY, LTD.
PO Box 27290, Prescott Valley, AZ 86312
Phone (928) 772-8262
Find someone YOU trust , and with some shotgun/ defensive experience and get trained up.
Rifles - yeah, sounds like you need to look into this as well.
Train the mind and mindset first. Then work on the hardware (guns and ammo).
Oh, I know it may be expensive for you to order from the US if you cannot locally for Awerbuck, another book, many of my friends in other countries do order, and the shipping is not cheap is.
Shotgunning: The Art And The Science - Bob Brister
This book will answer most questions often asked on Gun Forums. Seriously, I know folks in New Zealand, Spain, UK, Korea, Ireland, Jamaica, and other places that have ordered this book at my suggestion. This book has helped them a LOT! I care about folks "getting it".
NetNinjas can co use Dragon's Breath and Fletchettes for Suppositories for all I care...
Stay safe.
Steve