So I have managed to thread my XT brake lever so need to get a new one. When changing it over do you need to bleed/oil/do something as I have no idea when it comes to changing brakes! Or should I just get my LBS to do it lol

Yes you will need a bleed to refill the lever reservoir.
Best get bike shop involved if you’re not sure.

If you can bleed your brakes, you can do this job. It’s exactly the same, just with maybe a bit more fluid and a lot more air to come out.

I have never bled my brakes before – think I bought a kit though thats sitting at home somewhere!

The installation looks pretty simple! Guess if I get it wrong my LBS can just bleed them for me!

If you already have the kit, then it’s definitely worth a try if you don’t mind losing an hour or so once you’ve included faf. It’s easy, and as you say you’ve already got an unrideable bike and unless you strip the threads on the bleed nipple you can’t make things any worse at this point but could easily learn a skill and save some money!

Turns out I have the epic bleed kit. Says you don’t have to remove pads and wheel but other guides say you need too?

Remove pads and use the yellow bleed block in place of them. Then you get the correct amount of fluid in.

Replacement shimano levers come filled with brake fluid with a little sticker over the hole that the hose goes in. Makes it quite easy. I have done this twice and once I didnt even need to bleed the brake

Got new lever – just had a look at my old lever and when I pull out the hose there is what looks like some grey sealent type stuff on the thread of the old lever.

Is this some sort of sealent to stop potential leaks? Will I need to get some for the new levers?