I got a reply from Insight magazine, nearly straight away, after I emailed them. - I now have my 6 month subscription.
Definitely not a scam.
This is the reply I got from Insight magazine:
"Thank you for entering our magazine subscription giveaway on Facebook. Because we reached 2,000 ‘likes’ this morning, we are giving all our Facebook friends who email us a free online subscription. Your details have been entered and you will receive a notification shortly with all your login details.
If you are pleased with your win, we would love to hear about it on Facebook @InsightMagazine – thank you.
Happy reading!"