Do you have the Eurosport SD channels in your current TV package ? if you do then you need to order HD extra. I
if you don't have Eurosport SD channel then you need to move to a BT TV package that includes it and then order the Hd extra.
this link may be off use as it explains what channels and add/bolt ons are available with each package
Then using the link above posted by Zulu you need the Entertainment package. Give customer options team a call and see if you can get an upgrade 0800 800 030.
Still suggest that you ring customer option first. They maybe able to upgrade you for less than the cost of the separate Eurosport package. You never know.