I installed macOS Catalina. Now my 32bit Epson scanner does not work.

It has been no secret for the last two years that Catalina would only support 64-bit applications, and peripheral drivers. Your 32-bit epson scanner drivers will no longer work. Unless Epson has recently released new driver updates specifically for Catalina, you may find yourself needing to use the fee, non-subscription, 64-bit VueScan product.

VueScan currently supports 861 Epson scanners, and if you scroll to the bottom of the link, you will see the individual supported Epson scanners, and VueScan will advise if it can drive the scanner with, or without any Epson software.

Unfortunately, I uninstalled the Epson App and now I can't re-install it as Mac reads it as 32 bit. What a pain!.

You don't need the Epson App (or any Epson software) to scan with Image Capture.

Give that a try before spending money on VueScan. VueScan is certainly a better scan engine than Image Capture, but most people do not need that scanning capability. If you do, it is worth the money.

You may still be able to use the Epson scanner through Image Capture. Does it appear in there?