A few thoughts:
If you don't complete your PPL in Canada you won't be able to complete it here, as far as I'm aware. You'll probably have to go back at some point to 'mop up'.
For my PPL (Inverness), availability of examiners and weather for an extended cross country could have held up training significantly. It didn't, but it could have (and I'm sure that's true for anywhere within the UK).
I lived close to Inverness and did very little apart from learning to fly and revising for the exams for several weeks. If you're actually meant to be spending time with family (in-laws or your own?) then I'd be anxious about whether you can achieve both missions. If you can nip down to the airport whilst they're doing their day-jobs then it might work OK.
You will need some re-training to use UK airspace, and possibly before anybody will hire you out a plane. If you can afford to buy a permit type or share in such, and keep it close to Oxford, then do so.