I got off a GWR HST at Cardiff last night (43145+43069 on the 1727 Paddington to Swansea, to be exact). I then laughed as I watched my friend pile onto a rammed 150236 on the 2015 Maesteg to Gloucester (2109 off Cardiff).
Strictly speaking, simply stopping at a station counts as a visit!
In the spirit of the thread, though, the last one I visited would be Crewe on 18th April 2016. Expect a rather different answer in a few hours' time, although I doubt I'd have signal there, and a different answer again come 1700.
Bare Lane is the nearest station to my house, so my journeys usually start from there. Yesterday I visited Edinburgh Waverley, Inverkeithing and Burntisland. The latter was a new station for me. I also did quite a few of the Edinburgh tram stops.
Last station was Batley about 40 minutes ago but that's my home station so doesn't count. Last other than that was Leeds 15 minutes before that. Last new shack was Burnley Manchester Road 2 weeks ago today, last before that was Apperley Bridge in earĺy Feb.