If you wouldn't accept the offer anyway that's a consideration, but alternately just do the interview regardless and consider it as practice for any other interview offers you get

Note though in terms of your not wanting to move out - you should keep in mind that you're most likely not going to be based in one place for the entirety of your career as a doctor. Even in medical school as I understand you may well have placements scattered around the region of your medical school (sometimes across the county), and as a junior doctor you'll normally end up being rotated every 4-6 months to a different hospital across a given region (and some of the regions are quite broad for certain specialties and such as I understand).
My understanding is you also don't really have a way to guarantee you'll get to stay in the same region as a foundation doctor as I gather you just rank your preferences but ultimately an algorithm determines where your job is going to be and hence life for the next two years after graduating. Likewise you can choose not to accept a specialty post in a region you don't want to live in but then you may need to make a decision between a specialty you really want to do or reapplying repeatedly for a competitive specialty in your preferred region (or choosing a less competitive specialty in that region).
My point being, if you want to become a doctor in the NHS, sooner or later you most likely are going to need to move, so you might want to start doing the mental calculus on preparing for that now rather than trying to put it off
