@moley147 Hi and welcome.
PiStorm32 Lite with a Pi4B works well in the A1200 and lets you have loads of storage and extra RAM, wifi, ethernat and USB. Also HDMI out except for games, although you can use a Framethrower, which redirects the RGB output to the Pi, so you can just use the one HDMI monitor/TV.
Do you know about the various user group meeting within a reasonable distance of Cumbria?