Extras can be anything from £60+ per day on low budgets.
Adverts consist of two parts, day rate and useage fee. Day rate for most people in adverts can be as little as £200 sometimes even less. But the buyout for an advert is then added on top if you have lines or are considered 'featured' in some way- those are anything from £1k to £35K + if it's an embarrassing thing you're advertising that will 'mark' you as the Tena Lady girl, or the Chlamydia girl etc. there will also be buyouts for stills, POS etc qnd for different territories. Advert buyouts stipulate a length of time and if they transmit over that time it's usually the same useage fee +10-20%.
TV rates vary massively from £200 for walks ons to thousands per episode if you're starring, which can accumulate to millions over the duration of a TV series. sometimes films struggle to get funding and an A lister who believes in the project might waive their fee in favour of a cut of the films returns.
Theatre is usually £525 for a tour with a subsistence of about £150 per week but lower for TIE and low budget tours and far more once you are a 'name'.
I'm optioned for three years on something I've just signed for, but I have worked for expenses in the past and would do so again for the right project.
Actors seldom work all the time and it can be years between castings, so that money above goes literally nowhere.