Mail order site TOYZANDGAMEZ has both the OPTIMUS and STARSCREAM preview figures in stock (in their store and on Ebay) for £9.99 each. http://www.toyzandgamez.com/shop/shop.php?maincat=36&sid=sida096c2c65e43e9ccc866a2311f4e0322 I don't know if this is an official entry into Blighty or if they've imported some, but I thought UK TF fans may want the chance to pick them up: I just bought one of each. Pity it's Easter - Means a delay in receiving them! I do of course have to add the usual 'apologes if this in the wrong foum' caveat, but it's "news" to me!!!
I expect they'll be imported - toyzandgamez did the same with classics to get them before they were released over here.
Lot of their stuff is imported (I got Decepticharge from them!), so I don't think this is the Protoforms' first proper sighting in the UK.
I've ordered a set, if they have the usual multilingual packaging that the Euro releases sport I will verify this. At £10 each, this is probably the cheapest I'm going to see these at.