Spending parental leave abroad

I figured someone in this group will likely know the simple answer...

Background;

I'm a dual UK/Canada citizen and my wife is Canadian only. Were expecting our second child later this year and it coincides with our mortgage being up. We don't want to stay in our current area and I don't care about staying in my current job so we're thinking about her taking the 18 month parental leave and spending it in the UK. We have enough money for her to get the spousal visa for that time and I can easily get work with plenty of housing options with family. She won't work and we can spend some time with my elderly father while he's still around and our eldest can spend some time with that side. Once parental leave is up, we'd come back so she can continue her career and I'll get a new job.

Question;

For taxes, would there be any hurdles doing our taxes under these circumstances or would she simply put that she's a resident of Canada for tax purposes and I'd not be? At this point in our lives, everything just lines up right to do this and we'll never have an opportunity to spend this much time with my family again.

Edit: would her TFSA also still be tax free as we'd want to put our equity from the house aside until we're back to use as a downpayment on whatever house we buy on our return.