Guys I thought I would ask a few questions after reading countless BCU threads, but im still not sure about it.

Recently bought a ffrr ive only driven it a few times as its gone in for rust on sills, I noticed the steering is going heavy when I slow down to turn a corner.
I've read on here that it could be BCU, servotronic valve, the pump, the fluid or even a hose collapsing.
I won't have the car back for a week or more so I cant really check anything at the moment.

What I do know is my doors all lock and unlock using key fine, the boot does also, the mirrors also fold.
There is a noise of a fan near the heating controls it stays on when I turn the car off, how long for I dont know, but the land rover symbol displays on the screen when I lock the car. I've been opening the car door and pressing the radio switch to get rid of it just incase it stays on and drains the battery. If I switch the radio off it doesn't display the logo when locked.

When I bought the car it was at a guy who looks at suspension, the suspension wasn't working at all, it was basically doing nothing, but strangly there was no fault showing at all, the guy was puzzled as he'd never seen it before, so he ordered a replacement BCM but the car wouldn't accept it. So he put the old BCM back in and it started working again. He also fitted a new battery lead as the one on it was bodged he said this wouldn't be helping things.
My car is a late 2006 TD6 L322.

Do all BCM need coding.? It says on here that they are just a straight swap.

Or is the late 06 different.?

I'm buying a gap iid as soon as one comes available can it be done with the gap tool.?