If you are starting up, and don't know much about photography, and you're starting on a budget, I'd say a DSLR is the very last thing you should go for. And certainly not one that's getting rather 'long in the tooth' like the 500D. I'd say start with a 'point and shoot' that has enough manual overrides to allow you to learn the basics at your own pace.
You could pick up a Lumix LX7 for a reasonable price, which despite its quite small sensor, gives good results and would lend itself perfectly to a studio environment. Or then there's the Sony RX100 series which has a larger sensor and will give you results you would love. I wouldn't recommend a superzoom simply because you have said you will be mainly studio based.
If you can afford it, try to buy new rather than second hand. £150 on a new P&S will serve you better than an old DSLR for £99 which needs both lenses and knowledge.