Yeah, Frankfurt is big, always hated to fly from Frankfurt. They have such a long taxi in Frankfurt, more than once I thought if they are going to drive us to our destination instead of flying
But Heathrow isnt any better. So you changed planes in Frankfurt ? Did you fly Germanwings or Lufthansa ? Instead of the Bock you should have tried the Frankfurt version of Cider, "Appelwoi" (apple-wine)
You certainly would have got it at the airport.
Regarding the Maltese beer, might be the water but to me more likely is what you said about not being a lager drinker. Compared to Pale ales or especially Stouts or IPA's most lager are rather tasteless in my opinion.
However, you seemed to have enjoyed your trip anyway. Are there many Brits travelling to Malta ?