At the ticket machines / outside the ticket office.
I actually have a spare baselayer with me today. It's a bit tatty but it's clean (I think, well compared to me anyhow) - you're welcome to it. Note though I'm 5'8 and it's an xs uniqlo merino wool thing.
I've decided for train; @middleofnowhere @youramericanlover where do we meet?
Also I forgot the base layer this morning so be prepared for lots of ranting.