I know that road and it is real sorry to hear, I only live a 5min walk away. Do you think they have it on CCTV as their is the big office block opposite and loads of takeawaysim sure it might be on camera from somewhere so I shouldn't worry about being made to recognise them.
It must be quite common for victims to not recognise the attackers. Plus if they have witnesses to point them out thats good. Just perhaps focus on the extent of the injuries, don't go overboard but be honest. If it has affected other aspects of your life

bring them up.
I hope they get what they deserve (and if it is the wrong people thats being found innocent) From the sounds of it they will get whats coming and good luck.