Hey guys- just some hopefully helpful information if anyone else is thinking of doing this trip, specifically help for the Canada land border crossing in to the US.
I wanted to make sure I'd covered my bases regarding the Visa situations for both Canada and the US so asked some basic questions to a North American Travel Service and here's their answers (In bold):



"Is there anything I should be aware of/need to do to prepare documents etc for the Canada portion of this, or would just getting an eTA be sufficient?

ETA is sufficient

I already have a valid ESTA for the US, so I assume that that, along with my UK Passport is sufficient to gain entry into the US?

ESTA is sufficient but land crossing also requires an additional from completed at the border (I-94W) and payment of $6"


So in a nutshell- any UK Citizens thinking of doing this trip from Vancouver then south- all's you need is to get the Canada eTA and also a US ESTA in advance. Then once you're at the land border crossing there's a form to fil in and a $6 payment.
If anyone else has any more relevant info about this or if I've gotten it wrong, please feel free to correct me here and I'll update..!