Replacing Ultegra R8000 'long cage' derailleur (crash repair advice)
The Evans site is in error. Generally road derailleurs come in SS (short) and GS (medium) versions. The SGS long types are found in MTB groups.

Your derailleur may be scraped up but not bent and still servidable, the derailleur hanger typically gets bent in a crash which saves the derailleur. 

My experience of crashes where I've gone down on my side is the frame is fine as impact is taken by the bar, shifter, pedal and derailleur. Going over the bike looking for issues is obviously a good idea. I'd check the shifter, bar and stem alignment in particular.