Sad to say that I have reached my mid-forties before 'getting' St Thomas (and Aristotle). The Eureka! moment came with Dr Edward Feser's remarkable book, The Last Superstition which I thoroughly recommend.
The good professor's blog is tremendous knockabout stuff for such highbrow subject matter. To be praised by Sir Anthony Kenny as making Aquinas readable is praise indeed. To be sure Dr Feser's tone can sometimes be a little on the robust side , but he's taking the fight to Dawkins and the Dawkinseenies don't like it up 'em. In a page-turner of a treatise, written with much humour, Dawkins is shown in forensic detail to be the shallow schoolyard bully one had always suspected him of being.
By complete chance I was halfway though this book when I found myself looking through the book sale at the local swimming pool in Vancouver while waiting for the kids to finish a session and found (in amongst the Tom Clancy novels and the Mommy-porn) a copy of Maritain's St Thomas Aquinas (which I bought for 50 cents).
I'm ashamed to say that despite having attended a school dedicated to the Angelic Doctor, I can remember very little being said of him - I am pretty sure that in the spirit of the age (1976-1983) we were taught nothing of the greatest philosopher and theologian in the Church's history (Boff, Kung and Rahner got a mention, needless to say). I tried reading Copleston's account but just didn't get it.
I recommend Dr Feser's book (and blog). I'm starting a medical ethics degree later this year. Feser's grounding in Natural Law will be a good antidote to the fashionable nonsense I will no doubt encounter.
PS: note to St Mungo's bookshop - get lots of copies of The Last Superstition in stock.