Your computer can be upgraded to 16GB and the mechanical hard drive can be replaced with an SSD. Even without a failing drive, you'd probably find Catalina very slow on the machine as configured. At an Apple store you can get your RAM upgraded and drive replaced with another mechanical drive but unless policies have changed, the Apple store will not install an SSD. If you visit http://www.macsales.com you can watch videos showing how to upgrade RAM and replace a hard drive. They are easy repairs. Note: if you go this route I recommend that you also replace the SATA ribbon because they tend to wear out over time.