Let Canada join in too.
With the threats from the US, Canada could use some closer ties to Europe too. There are already historic ties to the UK that have weakened over the last few decades.
IMO there's some bad blood between the UK and the EU. The EU probably wouldn't want to just take the UK back after Brexit. And, from the point of view of the UK, the Brexit voters are still out there, and if the EU makes re-entry too humiliating, they'd raise a stink.
But, if you include Canada it's no longer just the UK rejoining the EU. It can be a new thing, the Canada-UK-EU pact: CUE. Conservatives who were pro-Brexit might be mollified because they tend to be more likely to be monarchists, and this can be seen as strengthening ties between two countries where Charles is the head of state. It also gives Canada and the UK a bit more bargaining power together than if they both tried to strengthen ties to the EU separately.
My guess is that if this allowed for freer movement of people and media, Quebec would be happy to have closer ties to France, Belgium, Switzerland and the other places in Europe where French is spoken.
We all should be working together to protect ourselves from Trump. And, even if the US survives Trump and elects someone sane as president in 4 years, recent history has shown that the US just isn't a reliable partner anymore. It's just too volatile and chaotic. Given the proximity, Canada will inevitably have strong ties to the US, but there needs to be some "plan B".