Thank you, Andy and Ian, for the warm welcome!
Looking back a few months on the forum, it seems as though my question about departing had actually already been answered. I think someone was advised that their 15:30 flight (probably the same one) is fine. And since that flight combination was the cheapest I could find (with earliest arrival vs latest departure), I booked it, before having seen your comments! I'm a bit new to this forum thing; sorry to have missed out on your advice!
Hopefully it won't be a problem.
Thanks again,
Sam