I would strongly recommend you seek another opinion from a good indpendent garage as it would appear the dealer is seeking work some of which may be unecessary and/or over priced.
For instance I reckon a decent auto-spark could fix the heater for no more than £200.
You could fit your own wiper and also if a wiper arm is worn you may be able to repair it yourself (there is a DIY fix on the forum).
It may be worth exploring why the
level and coolant levels are low - I suggest you tackle this aspect first in case there is a serious or expensive underlying problem.
The inner ball joints can be cheaply replaced at most indeopendent garages.
Depending on jow much driving you do the brakes may last long enough.
I reckon if you let a dealer quote for all the work the cost would outweigh the value of the car.
I assume you wheels are alloys which can be easily damaged on potholes, etc. You may be able to get a second hand set to suit but again any decent tyre dealer can check the wheels for damage and run-out.
In terms of priority I suggest you have the engine
leak diagnosed first.