I have a CTEK, supposed to be the dogs b's...at >£65 it should be, but turned out to not be very durable, lecky at work has since fixed it for me.
When parked outside i use a Maplins solar panel and that has been V good, also used one on the boat and proved to be weather resistant ok.
Otherwise...
Leave hand brake off, and chock wheels.
Make sure plenty of anti freeze/ anti corrosion additive. Ideally change the oil and brake fluids, but probably too late for that?
Yes - try to Move car a short distance at least every month or so, to avoid flat spotting tyres.
How damp/well ventilated is the garage? Keep it either well vented, or sealed up and dehumidified, perhaps use some of those window crystal things to prevent moulds inside?
I used to leave my car for 4-5 months regularly when working overseas.
The clutch on the TR5/6 was prone to sticking to flywheel, so used to keep it off with a piece of timber on the pedal/seat frame! Dont know if thats necessary with these cars?