Thats right Jayemm, if the cloud ceiling is circa 300ft you would have to divert to an airfield with a serviceable VOR/DME to fly the approach.
Perhaps the fact that the NDB approach has an OCH of 300ft doesn't bother you. Our NDB is bang on runway centreline and on the coast and therefore doesn't suffer coastal refraction. But if you prefer, divert to the nearest airfield (31DME North) and fly their VOR/DME(OCH 600ft). After you've gone around a few times, try the next nearest airfield (100DME+) to the south.
If you get lucky and make a successful approach, wipe your brow and think about getting the ADF fixed.