I reverted to my maiden name when I got divorced, but I didn't have any children at that point so it was relatively uncomplicated.
I have since remarried but decided to keep my maiden name. My dds have dh's surname with mine as an additional middle name. Apart from occasionally having to introduce myself in a fairly long-winded way, like 'I'm Ellbell XYZ, Babybell ABC's mother', it's not a problem at all having a different surname from my children. Generally once people know that I'm Babybell ABC's mother they don't have a problem with the name thing at all. Sometimes school secretaries and such-like do call me 'Mrs ABC' but I don't mind that - it's natural, since they know my dds better than they do me.
Have not taken dds abroad without dh but can't imagine I'd have any problems, since they do have my name on their passports as one of their middle names. The only people I ever had trouble with were the people at the Post Office when I went to get an 'old-style' E111 form. They wouldn't let me put my dds on my form as my dependents because we didn't have the same surname. I'm certain that they were wrong and should have let me do it, but we needed the form quickly and dh was there too, so I just let them go on his form instead. (And now, with the new cards they have their own card anyway, so it's irrelevant.)
So... that's a long-winded way of saying that if you want to change back to your maiden name, do so. The disadvantages are very minor, and personally I wouldn't want to spend the rest of my life with the name of someone I wasn't glad I'd married. (I don't even really want the name of the guy I am glad I married .)
FAQ/lostdad... I think you're at cross-purposes. Surely when schools ask for 'name' and 'known as' they are talking about first names (e.g. Alexander, known as Alex) not surnames.