Won't start.

My rusty old G's been laid up in a garage a few months, been making a point of running it from time to time, and keeping the battery charged, but at the weekend it wouldn't start

Turn the key, hear a relay click + the fuel pump whirring, but the starter doesn't try to turn, it's not taking any current since the lights don't dim. I figure maybe the solenoid's seized, but don't know much about polos, (though I am an electronics expert), wonder if there's a common cause? Also had trouble finding the starter, think it's at the back of the engine under the injectors + stuff, what's the best way to get it out? (hopefully I'm swapping the engine into the Mk2 in a couple of weeks, so could do it then, but really I'd like to have it working beforehand).

Any advice greatly appreciated.