The standard pay is usually about £50-100 / $100-150 per day. If it’s hourly, which is very rare, then you’ll be paid minimum wage or something close to that, but that never happens because extras are expected to stick around for however long the production takes, and that may be well into the night.
Can I wear jeans to an audition?
You don’t need to dress like you’re going in for a corporate interview here. Your clothes shouldn’t be a wrinkled mess, but you also shouldn’t be wearing business attire to an audition. A good pair of jeans can go a long way, and it’s worth investing in a pair for auditions alone.