You don't have to wait half an hour if using Potlatch (the online editor). You can just click 'Edit' immediately to the right of the track, in the listing.
The other advantage of doing it this way is that the waypoints come through. If I'm mapping an NCN route, for example, I'll usually log a waypoint at the point which it changes between on and off-road - it's really helpful to have these available when editing.
Andy, if there's any specific presets you'd like to see in Potlatch, let me know!
It's generally good practice to upload the tracks if you can - just so that if some bloke comes along and says "oy, you copied that from the OS", we can turn round and say "no we didn't, here's the track". But not essential.