A little late now Jim but for others who may find it useful…
Download the OPAL App to your phone, register your OPAL card (don’t need to link a payment card if not necessary). This not only keeps a track of your card usage and remaining credit but provides excellent travel information, both metro and bus, even alerts at your ‘stop’. On a land trip, pre covid’ I found it really useful. Following your posts is bringing back many memories of that trip, fortunately with better weather (except day 1 !!).
I’m editing to add that Citymapper is also worth looking at (about 400 cities)…