Below are the tools which are essential for working on these Zontes Motorcycles. They will also be useful for other mechanical tasks which you may encounter in the future.
Socket Set (1/2″ Drive)

This is a good, budget socket set which will work great for everything on these motorcycles. Amazon Link
Ratchet (1/2″ Drive)

This is a ratchet which I have being using for a long time. It is a good lightweight ratchet with a composite body. Amazon Link
Metric Allen Keys

Bahco make really good quality tools, and for £10 these Allen keys are really good quality. Amazon Link
Metric Ring Spanners

While sockets are good for bolts which have a good amount of access ( such as axle bolts) spanners will be useful for harder to reach bolts such as the bolts holding the carb to the intake manifold. Amazon Link
Screwdrivers

These screwdrivers are good for all-round screwdrivering and are cheap at £6.29. These will be useful for tasks such as carb tuning or removing fairings. Amazon Link
Pliers

Pliers are a useful tool for gripping the hard to reach fasteners which you may encounter, or even just using them for wire cutting. Either way this set is good quality for the price. Amazon Link
Funnel

This is a funnel which will come in really useful during oil changes, or even just for general fluid transfers. Ebay Link