Preheat grill to hot. Place tortilla chips in a single layer on a non-stick baking tray. Set aside. In a small bowl, combine Cheddar cheese and Red Leicester-style cheeses. Mix well. Set aside.
To prepare the salsa, combine tomatoes, spring onions, garlic, parsley and vinegar in a medium bowl. Mix well. Place 2 teaspoons of salsa in centre of each chip. Top each chip with 3/4 teaspoon cheese mixture.
Place baking tray on the grill rack. Grill 10 cm from the hot grill until cheese melts, about 1-2 minutes.
Using a palette knife, place nachos on a serving platter. Serve with the remaining salsa for dipping.