A surge protector does neither of the things the OP wants.
For fluctuations and low voltages you would want a UPS (uninterruptable power supply) to cover the operating load until power returns to the proper, stable level.
"I don't want to use my system when the power cuts out i just want enough time to shut the PC down and a UPS that can protect my PC. "
Excellent - all the better.
Hopefully all you need is 4 or 5 minutes to gracefully and properly shutdown the PC. Much less expensive than trying to run for an hour or so. Which may be moot any way if there is a general power outage and all ISP connections and devices are down.
= = = =
Look for product reviews for UPS's available in your area.
Or UPS's that you can be certain of being able to order and then receive.
Read UPS User Guides/Manuals. Visit manufacturer websites to read Forums and FAQ's. Look for what is said and what is not said.
Lastly: Backups. Ensure that you have an active and ongoing process to back up your computer OS (image/clone) and data.