Oh the joys of fruit trees!
Sorry I can't offer much advice, I tend to take whatever the weather throws at me, you win some, you lose some
Frost will definitely kill off the blossom and I think cherries, and plums, are the earliest to flower. Some years if the spring is exceptionally wet the pollinators can't get out to do their work. I used to be plagued by wood pigeons that stripped the buds from my cherry and plum trees every spring without fail, there is always something that will deny us the delicious harvest we long for......
If your trees are small then I would imagine some form of protection may be of use, I don't know about later flowering varieties, the 2 you have are the popular ones available from most garden centres, if you want to check out other varieties Keepers Nursery have over 100 to choose from.