Pretty much what Stan Drews said.
Some operators produce / issue driver duty cards / boards, some issue bus running boards / cards (the practice and the terminology varies from one operator to another) - so at the latter you would either need to trace the driver duties from one bus running boards to another (and then they wouldn't go in to detail about how drivers get between the relief point and the sign on / off point, or what basis they are paid on.
I'm not aware of any operators who put either in the public domain. TFL bus schedules are public domain (
here) and show driver duties, but they don't show the sign on point, how drivers get between garage (or remote sign on point - there are a few) and bus, how much paid time is allowed for sign on or sign off, or what the pay arrangements are. In London, most routes have their own duty schedule, but there a few where drivers will work more than one route in the course of a day's work for one reason or another, and more so where night duties are involved - most night duties will involve a short 'first half' on a day route (sometimes but not always the most obviously linked day route) as most night routes only run about midnight to 0500 now.
I think it's unlikely that any operator puts their duty schedules including paid time etc in the public domain, and would have thought most would take a dim view if anyone did.
There's very few standards - each operator has its own way of putting duties / rotas together, and some will have different schedules conditions at different garages / depots, either as a result of local negotiations, or because different depots were historically part of different operators, then there may be different rotas within one garage on separate conditions, e.g. most London operators traditionally work on a standard (say) 38 hour week (or rota average), but some routes lend themselves to longer duties and some rotas may be on 40 - 45 hours a week. Some operators (not aware of it in London but have seen it elsewhere) have adopted a basis of 4 longer days a week for some or all rotas.
In terms of breaks, pay 'sign on to sign off' is increasingly rare, some operators pay something like spreadover minus 40 minutes, unless it's a split / spreadover duty (where the break is more than X amount of time) - the middle bit of a spreadover may then be unpaid, or may attract some sort of allowance. Then you get in to the realms of enhanced 'unsocial hours' rates or enhancements which some operators still do.
Part time work on 'bus' work is still relatively rare, some operators have part time school route drivers, some operators have a small number of duties where drivers do (say) a 5 hour-ish duty that covers either the morning or evening peak, a few operators have rotas where drivers do (say) 3 days a week, but there's even more variables here.
