I never had vegemite, not sure if it’s available in the UK. As for Marmite, spread on bread so thick that it’s almost black and makes your eyes water when you take a bite.
Marmite on toast can tend to break the surface of hot toast up if it has been buttered. The latest discovery is to spread the Marmite on first, then apply the butter. No soggy surface. Also, put the Marmite into the microwave for some seconds. It spreads much more easily.
Marmite is absolutely one of the worst foods I have ever tasted.
And I’ll eat almost anything-frog legs, escargot with butter and garlic, haggis…