How can I get the T95/FV4201 Chieftain?
Like you suspected, the answer involves being succesful at Clan Wars.
To be specific, the top x ranked players in the clan wars tournament (you farm something called fame points by taking part in and winning battles with your team)have the chance to buy this tank for 4000 bonds. For everyone else, as long as you compete in at least 5 clanwars battles, you may enter an auction and place a bid of whatever amount of bonds you like in order to win one of a limited number of reward tanks (the pool is limited, and you may specify which tank you want)