[sceptic]

There won't be a Team Atomic Kitten.

Here's a more accurate predicition:
VX Racing - Vauxhall Astra Coupe
Yvan Muller; James Thompson; Luke Hines

Arena - Honda Civic
Tom Chilton; Alan Morrison

Team Dynamics - Honda Civic
Matt Neal; Gareth Howell

SEAT Sport UK - Seat Toledo
Jason Plato; Robert Huff

Team Petronas Syntium Proton - Proton Impian
Farique Hairuman; +1

GA Motorsport - Vauxhall Astra Coupe
Charlie Butler-Henderson; +1

GA Motorsport - Alfa Romeo 155
Carl Breeze; Paul Wallace

Carly Motors - BMW
Tom Ferrier; James Hanson

Kartworld Racing - MG ZS
Jason Hughes

Barwell Motorsport - Honda Civic
?; ?

That's 20 confirmed cars.

There are also a few possibles - some of which are more likely than others:

MG Sport & Racing - MG ZS
Warren Hughes; Colin Turkington

Vic Lee Racing - Peugeot 307
?; ?

Griffin - Peugeot 406
?; ?

Edenbridge - BMW
?; ?

Team Varta - ??
Richard Marsh?; ?

I'd expect 25-27 cars.