Deborah, as Fox quite rightly says, this is a tough one and I think you should seek the advice of an expert, maybe your first call should be at the Citizens Advice Bureau.
My gut feeling is that the reasons for the transfer, and which party terminated the contract is irrelevant. I believe the new contractor should take you on under TUPE, with protection of your wage rates hours etc.
However, reading between the lines, the client does not want you on site and my guess is that the incoming contractor will not take you on, or make your life there difficult - thus forcing you to leave.
Either way you will have a claim for unfair dismissal - whether outright or constructive.
In the event that this does happen you should follow it through the legal route - but get proper advice from a solicitor first.
I doubt you will get anywhere with the slander and defamation of character - but hey, it's worth a try.
This is an interesting one - would you be kind enough to let us know the outcome?
Musicman