If you are paid by the hour, then if you go to work for 10 hours, you get paid for ten hours - at least if no hour is taken off for “unpaid meal break”.
If you are salaried, you get paid the same whether you work 8 hours or 12 hours. 15 hours every day is illegal, but there are plenty in this business who work 12 hour shifts, get an hour unpaid for lunch, and are therefore “salaried for 55 paid hours”. over monday-friday.
If you are a tramper, then you might be paid for a 10 hour day, but when parked in a layby “off duty”, you’ll not be paid - except for the “night out allowance” which imo is small compensation for having hours 11-24 of your day ■■■■■■■ with the vehicle, which for security purposes, you shouldn’t leave unattended.
A 5-day 4-night tramper then might drive say, 9 hours per day, 2 hours on “other work” like loading, and 1 hour a day on meal break multiplied by 5 shifts per week. This would include 4xnight out money, which might be £25 per night. You are most definately NOT being paid for “all your hours away from home, at work”. In 3 years of doing agency, I’ve not been offered any tramping, so I think the agencies rather you not do it because being “paid by the hour” as you are on agencies would presumably mean that working from say, 9am monday to 8pm friday with nights out would pay you for every hour between the start and return home, and would cost the firm a fortune that they are not prepared to pay… Even at minimum wage £6.50ph, 9am monday to 8pm friday with an hour a day knocked off for unpaid mreal break would cost the firm a lofty £795.50 for the working pattern I’ve described. There might be some yards out there paying that kind of wage per week, but you’ll not hear about it because of the “dead man’s shoes” rule - such jobs are never advertised, because they are always filled in house, or by word-of-mouth. Remember too that £795.50 is the weekly wage figure based on minimum wage hourly rate when broken down. Net hourly rates are really not that good for trampers. Nights is better imo.
Typical pay for the work pattern described is around £500 - £600 with the 4x£25 night out money.
Whether paid by the hour on agency, full timer, paid by the shift, or salaried - you’ll not really ever being paid for being “off duty” in a layby, be it for a 45 minute legally required break, 11 hours daily rest, or 45 hours weekly rest.