If ur watch isn't in the list. Just select 'other' at the bottom of the list. U will only get a £100 for it. See if u can get more by selling it privately. I hope this helps.
As posted elsewhere Samsung have pulled a nice little scam on uk watch 4 owners. In the US you can get up to $240 trade in on a watch 4. In the uk you can only trade as 'other' for £100. Don't bother asking Samsung why. I tried this and they just ignore me. Nice customer service. Not!