Thanks both! Luckily DS was an absolute star and adjusted to the timezone very quickly! We decided not to change anything before we went and just accept that he might wake early for a few days. The first night he woke at 2am local time hungry, which corresponded to when he'd have his breakfast bottle at 7am in the UK. He took a bit of convincing to go back to sleep after that, but obliged. The second night he woke at 4am for breakfast, but then 3rd night he was waking nearer 7am.
On the way home, we just forced him to adapt to UK time straight away, but played naps by ear, i.e. putting him down earlier than we usually would, but we thought this was best given he'd only had about 5hrs sleep that night because of bad turbulence on the plane and then the timezone change.
Good luck to anyone who does something similar in the future with a baby - it definitely wasn't as hard as I expected!