We only have a 36mm open-ended spanner and a mallet. Works for us.
Peter
When I did mine, I just left the belt attached, put the spanner on and hit it with a mallet a few times until it came loose - didn't need to any additional spanners or tools.
Yes the fan will spin slightly, you just turn it back and hit the spanner again with the mallet and repeat - you'll shock it loose.
Join the D2 boys club forum (free) and you can get both the spanner and the locking tool for £25 or so from Ryan Wild. Super quality and daft not to at that price.
+1 for Ryans kit. Used them yesterday changing the "fan" belt.
Griff
I've signed up to D2BC, but how do I find Ryan to buy them?