In reply to HC~R not logged in:
Tyres... no chance. At least they're cheap on a Ka.
Leaky brakes... well if it passed an MoT just before you bought it then the brakes presumably weren't leaking then. Unlucky but it does happen and again, the parts should be cheap for the Ka. You could ask at the garage but chances are you won't get anywhere.
Clutch/gearbox... was it ok on the testdrive, you really shouldn't struggle to get gears on a modern car? Has it got gearbox oil, of course that's very hard to tell without draining the box? Clutch can fail suddenly but most likely it'll be a cable/oil seal (not sure if it's hydraulic). I'd go back, explain you're not happy, you think you were knowingly sold a dud, ask what they'll do then take it from there. Again, clutch parts are cheap, it's the time that costs so if they offer labour or some similar deal it might be worth considering.
Unlucky, hope they're decent and offer to sort it.
jk
<edit> Sorry, that sounds more negative than intended. Good luck.