Discovery Plus.
That said, I think we need to expand our thinking. As of today, there’s two options: Eurosport Player and Discovery+. Eurosport Player is supposed to be phased out in Jan but I’m not sure it will be phased out in every country.
Regardless, the price of either Eurosport Player or Discovery+ varies between countries in Europe. If you’re really trying to min/max you aren’t restricted to UK only, in theory you just need to find a way to sign up from any of the countries that will have Eurosport cycling coverage and ideally the cheapest country. You’re going to VPN it regardless and the different language feeds will still be available.