I’ve not done it before, but I’ve a feeling you’d have to collect your bags from the carousel, exit through customs, queue up for bag drop again and then go through security. If you could travel with only hand luggage and pay for priority boarding so you’re guaranteed to get it in the overhead it could be an idea. Also, if the first flight is delayed you’re fucked.
I’ve done collect and recheck through Standsted. Should be no problem with that much time. You can get yourself the fast security queue as well for about a fiver.
Is it the second flight that you’re inflexible on?
What time of day is your Dublin-London flight?
You’re basically betting on the Dublin-Stansted flight being on time or close to on time.
It probably will be, but I’ve had serious delays in the past on Ryanair (ex Stockholm Vasteras and Amsterdam). If it’s an early flight the likelihood of it being on time is higher and ex Dublin should raise that likelihood again - I’ve never had a serious delay on a flight out of Dublin.
But I would suggest a minimum of four hours gap to give you confidence that you will be in time to drop your baggage off for the connecting flight. If there’s any sort of delay with a three hour gap you’ll be sweating.
I can get out earlier alright but I don’t really fancy spending 6 hours in an airport. Only for the checked bags, it would be fine
My main question really comes down to the need to recheck in, I’m pretty sure I flew with British Airways before on a connect and I didn’t need to recheck the bags in for the connect flight. Not sure what the story is with Ryanair. If there is no need to check the luggage in again everything should be fine with 3 hours.