I think your budget is too low to buy a quality bike new. That is only equivalent to about £100. I'd say that reasonable quality starts at about double that. You are going to get something which is very heavy and has poor quality components.
If you can't up the budget to about that kind of level, my advice would be to spend the money on a quality used bike in reasonable condition. You'd really need someone who knew what to look out for or you could end up wasting your money on something that was worn out or wasn't that great to start with.
If you buy a used bike, ask for proof of ownership to avoid buying something which has been stolen.
Do you know anybody who knows much about bicycles who could give you some help?
You might find a bike shop with used bikes for sale. Don't go to any old shop - you want a decent bike shop. Some take in old bikes in part exchange when they are selling expensive bikes to customers. They probably just want to unload the old bikes as quickly as possible so you might pick up a bargain there. They ought to check such a bike over for you.
Since money is obviously tight, I'd warn you that bikes do get stolen even when locked up so try and find somewhere secure to lock it up like a storeroom at work. I don't what is it is like for theft in your part of the world but I'd be reluctant to leave a bike locked in the open in a lot of places here in the UK.
