heat takes FOREVER to get hot
 

Really it mostly never does. I mean if it's stop and go traffic it does fine, but i leave the house and drive 45 minutes on the highway, AND drop 2000 feet in elevation at the start of the trip. So I know it's not ideal conditions, but really, it should get warm, right?
I have a new radiator and standard thermostat I installed last year. I keep an eye on the fluid level and it's fine.
Any thoughts as to why it isn't getting hot?

Put the setting on manual and econ, if that does not work, check your heater core hoses under the hood to see if one hose is cold and the other is hot. If that is the case, clogged heater core.

Bleed it on a hill.

What coolant are you using? DeX or green?

For sure manual an econ. I'll check the hoses, good thought.
How bad is a heater core on these?

I use the hard to find basic green

It's probably not the core.

if you bleed it and bleed it and get nowhere, you can disconnect the hoses to the core and flush it slowly with a garden hose. Idk what your water pressure is like, but usually it's around 40-45 psi. Your heater core is made to hold 15.

being creative you can adapt a garden hose onto the pipe, crack the valve for the garden hose until some water runs out, see what the flow is like. If you get any gunk...then you need to evaluate.

when we used to repair the old style heater cores, we would repair them to hold 40-50 psi. The copper/solder would hold but these new crappy radiators with aluminum plastic is trash. The threshold for failure is much higher.

I guess I will try another bleed. I bled it hard after the radiator service. I just gotta find that procedure again.

when i first got my parts truck and was driving it home, the heater barely worked. sometimes there would be a burst of heat but most of the time it was just barely warm.
after i replaced the dead thermostat, the heater worked perfectly. however, i can't say for sure whether the problem was an air bubble or the thermostat not allowing full flow into the heater.

What standard thermostat did you buy? There have been some duds out there recently.

I'm not familiar with the setup, but you might want to check the blend door function. Very common on other vehicles to fail. Although I've never hear of it on a rover it would be worth looking into. Again, I'm not sure how it's set up but my Ram doors broke and it was freezing....sort of like you say. Around town was Ok, but drafty. Highway was terrible how cold your feet would get. I THINK there are 3 doors (flaps) on my truck which is dual zone like the rovers. 1 controls where air is going 2 controls zone/temp 3 is the recirc door.

It would be worth asking about, but how/where to check is above my pay grade.