Hello Mike_Coombes,
From your post, I understand your passcode is not working and when you connect your iPhone to iTunes it says that you need to turn off Find My iPhone. I know how important it is for your iPhone to be in working order for you. In a situation like this, I recommend using one of the 3 methods suggested in the following article:
If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled
Pick a way to erase your device
Unless you made a backup before you forgot your passcode, there isn't a way to save your device's data. You'll need to erase your device, which deletes all of your data and settings. Choose a way to erase:
- If you've synced with iTunes, use iTunes.
- If you're signed in to iCloud and Find My iPhone is enabled, use iCloud.
- If you don't use iCloud and you can't sync or connect with iTunes, use recovery mode.
Best Regards