Cripes, an SMG one! They're even rarer than the manual 'box, that's a great find!
Here's my take on everything, for what it's worth. The sensible thing to do is to get on the property ladder, as house prices and interest rates are only going one way from this point. It's NEVER going to be cheaper to get into the market now, and by doing so you set yourself up for life if you do it even vaguely sensibly.
That said, cars are a hobby, a passion. If you can afford it and know the downsides, then just do it as you're only young once. I spunked a fortune on cars before buying a decent sized house, but I wouldn't swap those memories for anything.