can I leave I Phone uncharged for two weeks will be away without phone

Apple advises to charge to <> 50% then switch the iPhone off till you are back.

From: Batteries - Maximizing Performance - Apple

Store it half-charged when you store it long term.

If you want to store your device long term, two key factors will affect the overall health of your battery: the environmental temperature and the percentage of charge on the battery when it’s powered down for storage. Therefore, we recommend the following:

• Do not fully charge or fully discharge your device’s battery — charge it to around 50%. If you store a device when its battery is fully discharged, the battery could fall into a deep discharge state, which renders it incapable of holding a charge. Conversely, if you store it fully charged for an extended period of time, the battery may lose some capacity, leading to shorter battery life.
• Power down the device to avoid additional battery use.
• Place your device in a cool, moisture-free environment that’s less than 90° F (32° C).
• If you plan to store your device for longer than six months, charge it to 50% every six months.

Depending on how long you store your device, it may be in a low-battery state when you remove it from long-term storage. After it’s removed from storage, it may require 20 minutes of charging with the original adapter before you can use it.

Why don’t you just switch it off? Ta

Ideally you shouldn't let the battery rin right down: I don't know how long it would take to do this. You could put it on a timeswhtich to charge for an hour a day (for example).

The battery will self-discharge, though it may do so slowly enough not to matter.

Why the switch? Why not simply keep it on the charger? It won't over-charge.

Suggest wearing the Apple Watch the last day, then turning it off. This will effectively be the same as when you received your Apple Watch. The battery partially charged and turned off. In this state you can keep it stored for an extended period of time.