The answer to your first question is almost certainly No.
As others keep trying to explain, whether you can 'sort' the rest really depends on what the actual admissions criteria are for the grammar schools in the area you are looking at. No school / consortium / LA (whichever is responsible for arranging the entrance test) can prevent you from registering your DD to sit the test, or from actually turning up and taking it, but it may well be that the determined admissions arrangements for the school(s) concerned are such that even if your DD gets the highest possible score, applying from where you live currently is unlikely to result in a offer on March 1st, or possibly at all.
For example...
The London Borough of Bexley essentially guarantees a place at any of its grammar schools (with an intake of the appropriate sex) to the top 180 highest scorers in is entrance test, with no condition on place of residence. However, for all the remaining places, allocation involves (just - no higher ranking for a higher score) having passed the test and then mainly proximity to the school at the time of application or within a very short grace period for moving into the area. So unless top 180, an applicant from a couple of hundred miles away has zero chance of an offer on March 1st and possibly none even if they move in next door to one of the schools sometime between then and September, if no places become available to the waiting list.
Similar arrangement with the vast majority of Kent grammar schools.
You obviously don't like Devon enough to want to just move a fairly short distance to be nearer to one of your own county's grammar schools, so presumably you do have some thoughts on what kind of area you want to live in?
Also you have reasons for not liking the nearest grammar schools anyway? What makes you believe that there won't turn out to be similar issues with a grammar school miles away with which you have hitherto had no contact at all?