Hi Tony,
A standard metric FAL hold open will fit the L1A1. I bought mine from Brad at gunthings.com. He can be difficult to get hold of, I just kept trying by phone. Once you give him the order he will ship quickly.
The hold open can just be switched.
I find it very useful, since when the mag is empty the bolt will just stay open and you can then put a new mag in, pull back the bolt and release to carry on, or put a safety flag in and remove the empty mag if you want to come off the firing point.
I've also ordered a butt removal tool for 15 dollars, and a long butt plate and screw.