Zed back tomorrow.. however, help/advice needed!

Hi all, just had the gearbox replaced on the zed due to the old one burning up, have got the new one guaranteed for 12,000 miles.. anyway the car still has some bits and pieces need sorting.. it has an oil leak at the back of the engine, and some waterleak somewhere at the front, also my heater blowes appear not to work.. what does this mean, that someone has bypassed the heater matrix?, also to sort out a leak at the back of the engine i had to remove one of the heating pipes as it was corroded and i made a gasket to block up this leak and seal it, which has knocked out my heating (although blowers do not work anyway), now my dilemma is.. is it going to be a better option to take the engine out to sort out the leaks, and am i going to need a new heater matrix?

help would be appreciated.. many thanks,

Will.