Get yourselves a decent coffee at the Vic Market (the nonperishables section, in the SE corner)on the Saturday morning before you go to Maldon. Don't worry about being too early, the place opens well before civilised people are awake. And while some use the terms "latte set" or "chardonnay set" to disparage others' attitudes, you'll be able to use plain English (even the Maine sort) to get a decent coffee made to your liking. And most places clearly advertise the size options. Although, if you're used to your caffeine as presented in US (a litre or so of something that tastes almost, but not quite, like coffee; to paraphrase Douglas Adams) you may be in for a surprise.

Cheers, Rowan