The RHS website plant-finder function shows suppliers for available varieties. The following are listed as available, with the number of suppliers listed.
Bob’s Tinsie (10)
Bright Buoy (2)
Ludgvan Red (2)
Mattie Cole (1)
Midnight Serenade (2)
Tama no ura (1)
Bokuhan is unmistakeable with its white petaloids. It tends to be an untidy, open bush, quite fast growing.
Happy Higo has huge flowers up to 10cm across, opening flat. fast growing with large leaves.
Kinsekai, Reigyoku and Portuense are amongst the few variegated camellias. The first two are very similar and very prone to producing all green leaves and shoots which if left will take over the bush. Portuense seems to be a very weak grower, perhaps only suitable for growing under cover.
Mattie Cole is usually more pink than red. The flowers are large, 7-8cm across and open flat. It makes a low spreading bush much wider than it is high.
Peter Betteley is in the National Collection at Mt Edgcumbe but as far as I know has nevr been propagated.
Tama no ura is probably not well suited to the UK climate and does not always produce its characteristic white edge.
Yuletide is a sasanqua, flowering in mid winter.