I am a great believer of being able to fix your motorbike on the go and always carrying a toolkit. That said, I managed to break down right outside a garage after filling up on the Brighton Burn Up without a tool kit last month. The only toolkit they had was a little cheap s chips Rolson mini toolkit.
This thing has been a life saver. It got me and 2 other stranded bikers home that day, then got 2 out of 3 break downs back on the road at the London Distinguished Gentlemans Ride.
Mix combine it with a multi spanner and fold up cycle tool, and thats a good compact starter toolkit to get you home through minor breakdowns.