Thank you so much for your replies, they're very re-assuring!
Firstly, some photos..
Simba:
Here is one of him sleeping:
http://imgur.com/m3NaN5T,9K2p1ah#0And another one of him (not sleeping):
http://imgur.com/m3NaN5T,9K2p1ah#1And the 8 week old maine coon X ragdoll
http://imgur.com/2zUL63K@sherry, they do have separate litter trays, beds, bowls & rooms.
I've made sure they can see each other from the crack of the door when they're eating.. Simba tends to growl at him but then carry on eating making his nomnom noises!
They made some progress today, I noticed Simba is a bit content after eating, he did walk up to Leo and rub his nose, then retreated, growled and hissed, but it's still progress :)
I was playing with them both separately, Simba didn't appreciate Da Bird being used for Leo as he's used to playing with it - when he saw Leo trying to catch it he ran up to him and gave him a slap - Leo didn't seem bothered, nor really seemed to notice and carried on playing but I decided that was enough for both of them.. They do have a nice tall cat tree which they tend to use and enjoy.
I'm going to slow things down a bit more and take it easy on them...
Simba is becoming more and more "adventurous" (or a psycho as the wife calls it).. racing around, chasing invisible things, rolling and tumbling around randomly, following me every where (for some reason he thinks it's always a race to see who goes down stairs first and into the living room on the sofa), meowing for play time - and that does make me happy.. as my cousin calls it "he's like the cats off youtube".. it's exactly why I wanted a bengal! Put a ball in a cereal box with a couple of small holes and that's him sorted for the next 45 mins..
I'll report back my progress as I go along, maybe someone else out there is having the same issue (or will in the future)...