I have a P reg Peogeot 306 and my brake pedal has gone floppy and therefore the brakes pretty much dont work

You might have a leaky brake pipe or seal. Do not drive it with the brakes like that. You need to check the brake fluid level under the bonnet. If it is empty you definitely have a leak which needs to be fixed before driving it. If you do not know what you're looking for get family/friend/neighbour to help.

Floppy brake pedal, or one that ooozes towards the floor is a sign of:
1. A weak master brake cylinder. The big round ''drum'' under the bonnet, directly in front of ur steering wheel, is the 'power brake booster vacuum drum'. Attached to that is a mechanical piston with 4 small pipes coming from it. (one to each wheel brake cylinder). That is ur 'master brake pump cylinder'. It slowly loses pressure, allowing the brake pedal to sink down.

2. You have a leak in one brake fluid line, & pressure is again lost. Still, some pressure should be exerted on the other 3 brakes, until ur fluid level sinks too low in the reservoir, & a big air bubble gets into the brake lines. FILL YOUR RESERVOIR, pump on the brakes in ur driveway, & look for a fluid puddle on the ground.

Any brake service shop can analyze the problem immediately. Use ur hand brake to drive to the shop. The handbrake uses cables & springs to stop ur rear wheel, no fluid is needed at all.