Main spanner sizes are 10, 13 and 19mm. There are some 8mm hex heads too and imperial sizes on the engine so 1/2" AF is worth having. I have a tiny 1/4 drive socket set that covers some small size hex head and Allen sizes, talking of which, metric and imperial Allen keys are very useful.
If you're going somewhere with little traffic and poor phone signal then a scissor jack (Porsche aluminium off of eBay is nice and light) and a spare tube, tyre levers and a willingness to get stuck in may pay dividends! Plus a footpump too in that situation.
