Per comments on original post sugar can be reduced to 75g, lite coconut milk used (despite Nigella's warning) and plain Greek yoghurt used in the topping rather than coconut yoghurt.
Made it with 75g of sugar and full fat coconut milk. The sponge was lovely and soft but tasted a little bland. That may have been my fault as my lemons had been knocking around for a while so I couldn't get much zest from them. Couldn't taste coconut at all (I guess it adds to the texture of the sponge rather than the flavour). A lemon drizzle topping may have been better and would have added some zing but would have to go lightly as too much could make the already moist sponge too soggy. It was easy to make.
