Does the smart charge on the alternator need to be connected for the ecu to work? Must I have a silver calcium battery? Will it run on a standard lead acid battery? I know it pokes +/- 14.5 volts and probably won't be a good idea. What does everyone else do? Just disconnect the plug?
Thanks in advance.

Your using the ecu so why not let it control the alternator ?

No problem with that. A new battery is only about £80 as well. BUT, silver calcium batteries suffer from excessive sulfation amongst other things. Not good.

What I am really asking is: Will the ecu allow the engine to start if I just don't use smart charging?

Without smart charging, it is a straightforward alternator.

i never bothered with the calcium battery on my Cmax i had with smart charging. A mate who is a mechanic never fits them when replacing and has not had an issue in 15 years.

You'll be fine with a Ca-Ca battery (usually marked as maintainance free but not always as calcium), the charging voltages are the same as Ag-Ca ford batteries.
Most batteries you can buy now are calcium tech anyway, conversely this is a problem with older cars as they don't produce the correct voltage to fully charge this battery type.

Dave