The DC65 is fast as stink!!! Izzi was doing well until a crash at Loretta's from what I heard. I doubt you will get them in the UK. Cobra is limited to USA for the most part. The prety much dominate the 50cc class as far as numbers and championships. Thats the plan for the 65's too. This is the first year of the 65 though so I'm sure there will be teething pains. I'd be willing to ship one over there but you'd always have to wait for parts unless you bought a bunch up front. Also I dont know about your rules but being a one bike might not work out for stock classes! KTM might actually be the best route for you?
the sikolene should work fine. Maybe your clutch basket has grooves worn in it. take the clutch plates out and inspect the basket.