Tough one, i think ultimatly tough shit you bought a cheap car and didn't inspect it properly, i think we all have been there.

Also no tape is going to stop a brake fluid leak, at best the tape was probably used to cover up a crack in a flexie or soemthing and as you have driven it's burst the flexie at it's weakest point, quite easy to say ok at time of test though really as it was a few weeks back. - You would have hard job proving that was leaking on the 18th december.

As for the tyre, the obvious has been mentioned, swapped alloys to steel after mot to sell it on, again something we have all done. & unless we are all mot testers i suspect ALOT of people who swap wheels/tyres prior to sale refit tyres that wouldn't pass an mot. As quite simply they have sat outside for the last three years in they're garden and are quite probably cracked everywhere. I have also seen tyres crack, and indeed bulged only on the inside edge.