Want doesn't mean they could though.I read a thread here about their logistical concerns.
What are the latest tanks the Entente using and their closest OTL equivalents?
Britain adopted the Fuller doctrine regarding tank and armoured vehicle design (One chassis of Armoured Car, Light, Medium, and Heavy Tanks and one chassis of Universal carrier. These would be converted into other kinds of vehicles as needed and would support basically Blitzkrieg esque tactics as a means of dealing with America in a future world war) so their tanks are rather different from OTL.
Pre-war: Chimera and Custodian.
The Chimera's basically a vehicle that has Matilda esque armour at the front but a more cromwell esque gun with the option to fit a 4 inch howitzer to make things go boom. (Side and rear armour is of course more vulnerable than the Matilda by a good deal.) It's rather slower than basically anyone else's medium tank which is regarded as a weakness. But it was well defended enough to scare the Comintern into adopting the 57mm as its standard tank gun. Well; it and its older matilda and valentine siblings anyway.
The Custodian is basically a Churchill VII with a turret more capable of fitting larger caliber guns and a meatier engine so it can go rather less frustratingly slowly (up to 25 km/h); it still has those goofy enormous tracks to let it basically handle any turrain. They can also fit 165mm demolisher cannons when they need a derp gun.
By the time Britain enters though they've moved onto the Carnifex and the Cairn.
The Carnifex is like the in between state of the Comet and the Cromwell and is well regarded for fantastic mobility and great gun depression.
The Cairn is rather akin to a lower tech Conqueror tank; like you made the Conqueror and the Churchill have a baby; made to fit a 5 inch gun. The intention behind the Cairn is to put something on the field that outmatches any tank in the world in terms of firepower and with that 120mm gun they've done pretty good at that.
They also have the Chameleon light tank and a pre-war light tank I've forgotten the name of.
The Chameleon is rather akin to the Cruiser V.
French vehicles:
The French by 1942 manage to roll out a vehicle based on this beauty:
http://wiki.wargaming.net/en/Tank:F11_Renault_G1R as their primary medium tank.
Their main heavy tank is rather ARL 44 esque whose main virtue are the incredible guns it can carry (either a 105mm gun with a significant amount of punch or a 90mm gun with truly world class penetration; the best of any heavy tank gun in the world until the Cairn arrives on the scene and they've got a light tank somewhat similar to the ELC AMX design going around; though the gun is rather smaller and it has a fully traversible turret.
While many end up serving Petain; De Gaulle and LeClerc's tank formations manage to escape to serve the Entente military among others.