Hello! First time back on this thread in a while been in FB and ill but had a 12w scan and lots of wiggling so pleased with that!
I travelled quite a lot in my last pg and it was fine apart from one run in with a useless GP who nearly made me miss my brother's wedding and charged me £50 for the pleasure. Still, better safe than sorry!
Airlines (and ferries) require fit to fly from typically 28 weeks and stop you travelling at 36 (it's sooner with twins Clare so double check). It varies by carrier too. Lots of airlines have a form you can print which your midwife / GP may be happy to sign at a routine appointment as it basically says 'I have seen this person, right this second they are OK to fly'. This is often free while requesting a 'fit to fly' letter from the GP may need to be done a couple weeks ahead and carries a charge of, in my experience £50. I was surprised to learn it may only be based on them flicking through your notes (even if they request to see you as part of this process), which if you've been seen at 16 and 25 weeks, and have to request by 30 to fly at 32 the note may be effectively useless as it's (a) based on info too old to be reassuring to anyone and (b) superceded by the 31 week check, which may say you're not fit to fly after all. So a quick signature after a routine check is much, much better IMO but I understand not all will do it.