There are some very big flaws in your argument.
Firstly unless the EU parliament ratifies the deal agreed before Christmas then the UK has no deal with the EU and we default back to WTO rules. So unless BoJo stops his belligerence over the NI protocol and the EU ambassador's diplomatic status then we probably will have no deal. So then the loss of trade would be a lot higher than 30%. But even £200bn is a massive amount to be made up for through trade deals with other countries. That needs to be recouped now, not over the next however many decades, now!
The relationship between the EU and the UK has been going sour ever since BoJo threatened to break international law. The UK and EU have been briefing against each other ever since. I see both sides as equally guilty of briefing against one another. I believe once the realities of Brexit start to kick in and the UK is shown not to be the powerhouse that Brexiteers believe it is, Britain will be forced into applying to rejoin the EU. Just in the same way as the UK needed to join the EEC originally. The UK currently stands alone as an unproductive mess of an economy that is heavily reliant on services, house prices, and debt. As one journalist put it recently, "every country and economy in the world will want to build back better post-Covid, but the UK is going to do so without any plan or way to accomplish it".
Begging to join the CPTPP is sacrificing the sovereignty that Brexiteers claimed was so important. We will be forced to obey rules we have no hand in making. Seems its perfectly fine for the UK to have to follow rules it didn't create just so long as it wasn't the EU that created them.
I don't believe you ever were a remainer really otherwise you have properly bought into the Telegraph and Express propoganda.
If you think the UK will be re-joining the EU in the near future then I think you are deluded.
The EU did themselves no favours in threatening to invoke article 16 over Northern Ireland and seems to show a distinct lack of understanding over the Issues of Northern Ireland. Brexit and Northern Ireland with the UK out of the Single Market and Customs Union was always going to be a difficult problem and only the Brexiteer Hard Nuts would deny that, however both sides now need to dial down the situation and find solutions.
Well if you don't believe I was a Remainer that's fine, I was it has to be said a luke warm Remainer who didn't like many aspects of the EU but voted Remain on the basis of the economic damage it would do, and that ideally it could be reformed from the inside although from what I have seen of the EU of late I don't think there is much chance of that, so in that respect I am beginning to think that perhaps leaving the EU might well be a better long term option but yes there is certainly no certainty in that, and in terms of our industrial and agriculture sectors there are clearly going to be winners and losers.
Boris must know that the consequences of a No deal and WTO are significant for some sectors, otherwise he would have gone for No Deal, But its also very important to the EU as well so I think that when push comes to shove its unlikely it will not be approved by the EU Parliament.
I haven't read every detail of CPTPP but I get the impression that the conditions are not that much more difficult than you would get on most Trade Deals and certainly nothing like the EU that's for sure, I see no issue with looking for a trade deal with CPTPP and unlike the EU you can still do individual trade deals with CPTPP countries if you can not find a satisfactory CPTPP agreement.