Thanks all. I took the advice, booked Business and upgraded the return leg to First. I have never flown Emirates First before - I did BA F last year but I suspect this will be a whole different level. I have enough points to upgrade both ways but have resisted for now in the hope of finding another way to spend them.

When I got the Emirates credit card, I redirected a lot of spend to it, so that I didn't need to pay for business class, and use the points to upgrade from economy. But I can see that I'll end up paying for business and upgrading to first instead. I had never flown business at all until last year, but as you no doubt agree it's hard to stop once you start!