Isn't XCode meant to be free? I have a Mac running 10.7 Lion. I have the lastest compatible XCode installed but it isn't able to work with my iOS 10 iPad. It will work with my old iOS 6 iPod. I wrote an extremely basic app which compiled successfully and ran fine in the virtual device, however the system won't let me run or install the app on my iPod. I see I have a certificate issue and to obtain one I need to be part of the Apple Developer Programme.

I'm guessing that in the latest release of XCode this won't be an issue, and I can make apps and run them on my iPad for free as long as its for personal use. I know my Mac can't run Sierra but if I got hold of one which could would this be the case?

I don't want to have to pay a £99 per year Apple Dev Prog fee.
The actual problem is that side loading of apps without needing an Apple signed certificate was added to iOS 8. You'll want to upgrade your iOS and Mac OS to get to the level where Xcode can self-sign and self run based on your free AppleID instead of a paid and signed developer certificate.

It that fails, you would have to get a newer device to use the free entitlement of running code you self-sign and side load from Xcode.