From The Independent (but nearly 7 years ago):
£10-£15: Ten minutes with a street prostitute.
£20: Sex in a "walk-up" – rooms, usually in known red-light districts, which are crudely advertised with signs on the doors or walls. These establishments are often destinations for trafficked women.
£25: Entrance to a sauna, which covers the cost of the room and use of facilities. Sexual services are extra.
£40: Probably the lowest fee to engage the services of someone advertising in a phone box. A full hour will cost about £100.
£50: The minimum price for 30 minutes with a prostitute in a brothel.
£80: Probably the maximum charged for full sex in a sauna.
£200: One hour with a "high-class" independent escort, but they will usually ask for a minimum booking of three or four hours.
£3,000: An entire day with a "high-class" independent escort.
£5,000+: One day with a "courtesan", although they are unlikely to accept bookings for less than 48 hours.
Actual (total) earnings can vary enormously though. Some of the girls on the street in Ipswich can be seen waiting for hours (or possibly all night) with nobody interested in their services. At the other end of the scale, I've known a woman in Ipswich who runs a very smart escort agency where all of her girls (as well, of course, as herself) declare their earnings and pay tax at the higher rate, even those who only work one or two days per week.