No great espresso at LHR but I would say that short of indeed flying to Australia or Italy, the CCR one should be among the most decent in the terminal and should suffice. I'm also not a huge fan of the Union. To me, it is one of those "coffee for people who do not like coffee", but I should warn people that I tend to be a ristretto sort of guy, and like it bitter enough that you can feel a faint taste of almond when you drink, so am generally underwhelmed by the coffee "parti pris" you get in much of the UK.