Thanks for all the replies! Pouch an excellent idea.
Have checked with the airline before booking. couldn't book them as 2 infants, but as 1 infant and 1 child (paying child fare of course, but added bonus of full baggage allowance!). As long as older one is over 6 months and sits in forward facing car seat then its ok - hence the dilema of having to carry the bigger car seat onto the plane! Flying with Aer Lingus as no other airline would let us do it.
MrsBadger, you're right! I was able to book a porter for Edinburgh airport - she'll meet us in the set down area and even come with us to drop off the hire car and bring everything back to the terminal to check in! Cost 23 quid, but they also help you through the security check (skipping the queue!) and right up to boarding the plane! yippee! (now I just wonder if they'll help feed one of the babies too!!!)
Have tried contacting our arrival airport to see if they do something similar, but have emailed and phoned with no response. Grrr - webiste gives the impression that they do have this service, and that they are oh so fabulous at customer service - there, rant over!
Will definatly swop the changing bag for a little rucksack for the journey.
Thanks all! Feeling more confident about it all today....just need to keep repeating "I am strong confident woman, well able to cope with my 2 children" - despite my mother thinking I'm going to cock it up (must make sure I also look fabulous when she mets us, not the frazzled mess she's expecting!)