You don't need a visa to transit through Heathrow if you have a valid Canadian visa and a short (less than 24 hour) layover. Nor do you need one through Frankfurt or Munich.Yeah i did that too..wanted to get confirmation from the embassy but they dont provide such info.
There was a flight via Frankfurt and upon inquiring german embassy they say no need but the lay over was 2.15hrs so dropped the idea thinking it was risky cuz of any flight delays from the previous flight or the hassle for going through check in again.. the price was cheaper than Heathrow also..dont know what to do
2.5 hours is not a bad layover, I've done shorter, but if you're travelling for the first time and you have family (small kids?), then a slightly longer layover would be better.