For anyone interested we decided to go with this:
https://www.cookwithnabeela.com/recipe/tandoori-leg-of-lamb/
(Scroll down for video).
It's marinating nicely in the fridge now. It will be slow-cooked all day tomorrow. I have made another bath of keema aloo brinjal curry and will knock up a tomato and lentil dhal tomorrow. It will be served with chapatis, mint yoghurt and chutneys, and of course Strictly. Wine may accompany :-)
There will be plenty left for the following day and some to freeze down too.
We still have two legs of lamb left after this so will mull over suggestions again and any more appear. Thanks again.