Just a note to be aware that airlines are still cancelling flights even into Spring. In late spring, I'm flying to Berlin on BA, to which I have a layover in London. I made the reservations back in November and had a very nice schedule where I'd spend only about 2.5 hours at Heathrow and had an early enough European flight to unpack and have a nice dinner in Berlin. Sadly, it was too good to be true and BA cancelled that flight. now they either have morning or evening flights for that day. So I don't get into Berlin until after 7pm at night and have to spend around 6 hours at Heathrow.
I'd imagine it's because budget airlines have cut into BA's European business. I joked to the representative that I think I've spoken to every customer agent at BA for this one trip. Plus it doesn't say much about BA''s reservation system that the flight they automatically rebooked me on left Heathrow at the same time my flight from the US arrives.
But it's a good idea, especially if you book early, to keep checking your flight details as they may change.