2006 Vauxhall Corsa Expensive Car Repairs

I recently took my car to my dealer to have them look at the car heaters as they weren't blowing cold or hot air. When they had a look at the car they presented me with a list full of repairs totalling £1500. I couldn't afford this and had to take the car back without the repairs on the hope I could get the repairs done independantly for cheaper. The repairs include: oil in coolant bottle/suspect side gasket, no anti coolant, rattle from timing chain, oil pressure switch passing oil, drive shaft seal damp, cv boot insecure, oil leak from sump gasket and the whole heating system needs repaired - New fan, resistor and motor. Which of these would you say are the highest priority?