Would you serve this alone, like a pudding, or on toast/scones etc. Just trying to understand how to use it.

It's also the filling for their lemon tart, chiffon lemon tart (lemon cream folded with whipped cream to lighten it, could be used between cake layers, etc. But I wouldn't judge you for eating it like pudding, it's a really good lemon cream.

Yes, you could use it in any of your examples. Just wait till you try it on warm gingerbread!