Are they really that strict that they would stop us for 1cm if we did get stopped??
Yes - expect to see Ryanair staff patrolling the queues at the gate with the dreaded cardboard box. If they can't slide it over they'll make you check-in the offending bag.
Im hoping that because they are very popular we wont get stopped
Just because lots of people use them doesn't mean that Ryanair will let you off. Ryanair's cabin baggage sizes are smaller than the standard size used by most other scheduled airlines and hence what most luggage manufacturers advertise as being suitable for carry-on baggage. The responsible ones point out whether that excludes Ryanair or not. Frankly I think it's no coincidence that Ryanair does this - catching people out in the boarding queue is a nice little money earner for them.
Fingers crossed anyway.
And it's a nice little money earner because the charge for checking in a bag at the airport can be up 4 times what it would have cost to pre-book and pay in advance to check it in. So a bag that would have cost you £15/20/25 to pay for in advance could cost you £60/80/100 if they take it off you in the queue. Cheaper to buy a smaller case that does comply with their measurements or else be ready to hand over the plastic before they allow you to board.
Emma, I'm guessing that you haven't flown with Ryanair before? There are two key things to always remember and never forget with Ryanair:
1) You only get what you pay for.
2) They implement their rules and regulations to the letter and make you pay for it (literally!) if you don't.
In your situation I wouldn't be relying on crossed fingers unless I was willing to cheerfully cough up the money to have the bag checked-in if it was taken off me in the boarding queue.
There are some airlines that I would chance blagging it - Cubana has a very generous check-in luggage allowance of 32kgs for international flights but even so on one memorable occasion I turned up at Gatwick with in excess of 50kgs! I got away with it because I could happily open one of the cases and prove that it had educational materials in it that I was taking for a local school in Santiago. But even so I had a friend tee'd up to take that case home with her if they refused to let me check it in. Their allowance for internal flights is only 20 kgs and I've got away with more by carefully saying that I understand that the excess baggage fee is 1CUC per kilo and making it clear that I don't have time to wait for a receipt. But that's Cubana for you - I'd never ever dream that I'd get away with something similar with Ryanair.
SM