private car buying/selling, what are the ins/outs

i have the opertunity to buy some vans & cars cheap, but obviously if i cant make profit due to that dick the taxman then obviously it makes the vntur null n void & not worth while

 

i dont even know how mny cars/vans you can sell a year as just me myself & i doing so,

 

i'm not a trader obviously & i dont really want to be one as the few vans & cars i have the chance to buy cheap sell high for profit i could'nt earn a livining from but then then the way the govermnt budget things no bugger could make a living being "genuinely" self employed etc etc

 

what ar the ins & outs i need to be aware of or whre can i find out as i have been searching the web for info & to be honest i'm struggling to find definitive answers, it seems a contradictry setup but then as with most "official" gumph my interpritation may be the opposite to how it should be

 

i'm currently in between jobs yet again, fckin twmpory contracts etc etc so the extra cash could com in handy now what i mean harrys/harrits?

 

all info truely appreciated