He's loose in that he'll attack unopened pots or when checked too, but I'd seen a few occasions where he folded when he was played back at.
Not only was this my first 3bet but I think it was the first one on the table for the night, so i'm hoping for it to get the respect it (doesn't) deserve
So he's aggressive then, not loose...
It's a £30 double chance - people don't like laying hands down pre-flop once they've entered the pot.
And you're still in the double-chance period - 'first 3-bet of the night' doesn't really mean a lot.
You did an unnecessary bluff and are now priced in to call.