Well quite a bit to be honest. I'm not very good at games which require fast mouse and keyboard skills, but luckily WoT is usually more about positioning and tactics. I won't go into details about the game itself, there is enough of that around on the net if you dont already know and are interested, other than to say its a first person shooter except instead of a soldier, you get a tank, and you end up playing in 15 a side battles to either kill all your opponents or capture their base - all fairly basic stuff.
Anyway, here is my current "mount", the A13 Mk III Cruiser Mk V Covenanter, here pictured in my garage
In "real life" this was a bit of a dog. It was a rushed development that only saw service as a training vehicle, mainly due to its tendency to overheat at the slightest provocation. As the main theatre of operations at the time was the Western Desert, this was not a good trait. It also lacked armour and the 2Pdr was already starting to be shown as incapable of threatening the current generation of German tanks such as the PzIII.
The WoT version is rather different, and serves as a good example of why WoT and the "real world" should never be confused :-). In WoT, the Covenanter is something of a pocket sized killing machine. The more observant will have spotted the gun on my Covenanter is not a 2Pdr. WoT allows you to develope your tanks by researching and adding new equipment. This is the research "tree" for the A13 MkIII
As you can see, one option is to mount a 40mm Bofors instead of the 2Pdr. I'm not sure if this was actually possible, and in the real world why would you, but in WoT this gives you a rather nasty ability to put a clip of 4 rounds onto a target in about 2 seconds. Penetration is much less than with the 2 Pdr, and after the first shot accuracy goes out the window, but if you are in close, and shooting at the thinner sides of targets. that doesn't matter too much. That's the key, and the ability to switch to a better but more expensive APCR round if you run into something a bit too big. That, and the Covenanters reasonable speed and maneuverability allow a patient player to do rather well supporting the team by scouting and killing off light tanks and tank destroyers from the flanks, then using the time honoured tactic of running away if something big arrives.
There is one thing that WoT has helped me understand about real world tanks, and that is the importance of gun depression and getting hull down. As a wargamer I read many times how NATO tanks had an advantage in finding reverse slope positions, and how Soviet tanks were at a disadvantage due to their poor gun depression. I never really understood this, probably because as a wargamer I see flat open ground as, well, flat. In reality there are always bumps and dips in the countryside too small to be represented on maps or games tables, and our hills are well defined - our table goes from flat to 40 degree hill and back again with nothing in between. WoT has showed me just how important that advantage is, so for instance a Centurion can find a firing position where only the gun mantlet is visible to an enemy, where a T55 would have to expose the whole of the hull.
See, computer games do teach you stuff :-)
and the sad pathetic wreck when it goes wrong, but I should add I killed a KV1 and an M5 Stuart, plus damaged two more KV1S before they caught me, so a fair exchange :-)