From personal experience getting the bus pass for living on campus is a bit of a waste. It really only works out to be worth it if you are having to travel most days a week from town to campus. When you are in first year you can make use of the Young Persons Bay Dayrider, which is £2.80 compared to a return which is around £3.40 (unsure if this last one has changed over summer). This will allow you to make as many trips into town and back in a day as you need, as well as go all the way into Morecambe and Heysham for no extra cost.
My first year was unfortunately in lockdown, so I don't know how much I would have gone to town otherwise, but you could always try and time shopping trips up with when you will be going into town anyway (either in the day or the evening) to save some money.
In second and third year the bus passes are definitely worth it and are very convenient but for living on campus I would say there is no point.
Hope this helps, if you have any more questions let me know!
- Laura (Lancaster University Student Ambassador)