EKT 395 was issued, as you say, in Kent. The issue date for EKT registrations was between March 1938 and March 1939. The 395 would suggest it was issued in 1938. The machine does not appear to have the additional return springs on the front forks introduced for the 1939 model year and the rear light appears to be consistent with the 1938 pattern (1939 models had a central 'torpedo' shaped light unit)
Regarding the NH, N refers to 350cc and the H designates it as being a Red Hunter model
Here is a copy of the details of the 350NH from the 1938 sales brochure:
The registered number does not come up with a match on a DVLA vehicle search (so it is not on their compurterised system) or on a search of insured UK vehicles. However, this does not mean it is not still out there somewhere.
Hope this info is of some help