Avbor,

Canada & the UK may decide that CETA continues to apply to their bilateral trade, with the necessary tweaks regarding references to EU institutions, post-Brexit. Australia & N Z may also offer trade deals to the UK on that same pattern.

However, these 3 countries & the UK have little to offer each other as trade partners in today's economy.  Further, Australia & NZ remember bad experiences of severed UK markets when the UK joined the EU.

India, China, Japan, the US, the EU & other major economies will offer to explore trade agreement possibilities with the UK but those negotiations will be protracted & difficult when it comes to details (as will the negotiations with Canada, Australia & NZ) & will not begin until after Brexit.

UK Agreements will not be a priority for these other countries and each will squeeze the UK during drawn out negotiations while the UK languishes outside the trade blocks.