I think what's going to be interesting to watch, for both America and the UK, is the practical reality of having to negotiate and renegotiate trade deals with individual nations where broader regional/group deals are withdrawn from. I think in theory it's one thing (namely it can be projected or spun as a fast process) but in reality it's another. All this talk from Donald and the conservatives in the UK about "quickly" doing anything with regard to new trade deals, I think is pretty absurd. It takes years and years to negotiate a comprehensive and thorough trade agreement, and it's entirely possible that these two nations would have to do this with dozens and dozens of individual countries if they both stick to this thought of "we're going to eschew the status quo with trade agreements."
I also wonder if Donald knows yet that China isn't a party to the TPP.