It varies. For one thing, there are several different types of CSA (On Board, Retail, Platforms, and probably more), at different locations through the network with different rosters, and different T&C's!
What location and what role are you after? I might be able to help a little more with that knowledge.
For example, On board CSA's at Wolverhampton and Euston for the most part are either permanently working earlies or lates (normally the latter for new starters). Other depots (Preston and Glasgow I know of for definite) they work both earlies and lates as part of their roster. Most full time On Board CSA's work a 5 day 41 hour week, most weeks it's Monday to Friday but occasionally you work one or two days of the weekend instead. It normally works out that every few weeks you might get a slightly longer weekend.
Full time Platform CSA's are usually on a 35 hour week, either 4 days or 5 depending on role and location, with Sundays outside the working week, paid as overtime at an enhanced rate. For the 4 day week, you'll often find yourself working 7 days on, 2 off, 7 on again, but then you get a whole 5 days off. The 5 day week pattern gets a bit messier but there's normally some longer weekends in there too. Retail CSA's were pretty similar at least at the place where I was, though that may well vary by location.
Both of the station CSA roles can also sometimes be GPR, General Purpose Relief, where you don't actually have a roster as such, you only find out each week what shifts you're working the following week.
Train Managers and Drivers have a whole different pattern of rosters again!
