Well for small modest hire charges you could try your local library. If the music librarian is worth their salt they've got the good stuff and you can cross check for the best recordings with the Gramophone or Penguin books of Classical Recordings.
The recordings tend not to be free I'm afraid for two reasons. The first of which is that struggling record companies such as EMI and Warners have noticed that their classical music labels show a steady, unspectacular profit that is very predictable and very soothing on the balance sheets. It's a chunk of money they know that comes in as there isn't much in the way of classical music piracy. For a short time they were foolish enough to cut way back on releases relying on the old core of classics being re-released, but fortunately they've figured that a higher profile can help them shift a few more and so they tend to invest a fair bit in live recordings. Whereas classical recordings used to be difficult to record live, and cost a fair bit, now it's a lot cheaper and easier - way cheaper and easier than making a studio album in fact. So they tend to help fund and promote concerts both popular and niche and reap the rewards with simultaneous recording. It works surprisingly well.
But the only way artists can afford to do this is by getting coin in their pocket, there's no such thing as advances in their world. And tickets don't always cover the expenses. Buying old concerts helps pay for this coin and keeps the evil mega-global record companies interested.
Now, this doesn't help you get free music but it does show why you should buy classical music. However! All is not lost, I can probably find you some free stuff online, be they tasters or something more substantial. If that fails and you just want some of the greats I'd be happy to mail you a few CD's stuffed full of what I consider awesomeness. Also, if you check charity shops you'll frequently pick up bargains, and the Naxos label work miracles with really great CD's being available for £5.
Anyway, I'll poke about and see what I can find.
If you're after good books on the subject, Seb Hunter's 'Rock Me Amadeus' is a very funny and very good primer. Penguin's 1001 Classical Recordings I Have to Hear Before I Die is excellent. Also try asking your local librarian if they have Grove Music Online -
http://www.oxfordmusiconline.com chock full of articles but subscription only. There's other websites but I have to scoot off to work now. Let you know later.
(Says Mr Librarian)