You might only have £1,000 to spent but that does not mean that you have to accept a shed on it's last legs. Chances are slim that you are going to pick up a low mileage 2 owner car with Full Dealer service history, so don't even bother looking and if you do, don't get excited because the 'too good to be true' cars are usually the worst out there.
My personal advice would be to find someone, ANYONE that knows one end of a spanner from the other. I'm a massive advocate of cheap cars but this end of the market is more dangerous than a mine infested shark tank and you'll do well not to get ripped off if you don't know what you're looking for. If you're not confident you won't be able to spot a major defect, find somebody to come with you that is. Ignore at your own peril.
Don't get caught up on silly detailed that would send other people walking away on. Expect some electrical items not to work, the tyres to be mismatched/worn, the interior to be past it's best, the bodywork to be dinged, scratched, etc. You're looking for a car that drives well above everything else.
I'm not sure what type of car you're after, but remember 95% of the people with £1,000 to spend on a car want that is small, economical, modern, etc. As a result the prices for these cars are driven up, so it might be worth looking into slightly larger cars to get more bang for your buck. The family work horse A4 is a great example. A comfortable Recently serviced family saloon with full MOT & Tax for £600. You'd struggle to get a Saxo for that much.