Aylesbury is more in the south of England than the North. here is the Shodokan link - which you will probably have - it looks like the closest dojo is London and from a travel point of view either Bloomsbury or Angel would be the easiest from Aylesbury by Train. Could be about an hour's travel and I would reckon that Bloomsbury is the closest.
Trust this helps
http://www.shodokanaikido.co.uk