The diagnosis of whether or not a fan works when the engine temperature heats up is not speculative; the fan either works or it doesn't, and that can be definitely confirmed by just looking at the fan. If the fan does not work when the coolant teperature rises; it WILL cause the engine to overheat. If the fan is not repaired because you have already spent all your money on previously misdiagnosed problems; the engine will continue overheating as long as the fan does not run. And there is a significant risk of major engine damage from a blown head gasket or a warped head, if the overheating continues. The head gasket may already be leaking; and that would now make the engine overheat even if the cooling system were restored to absolutely perfect condition.
If this problem is to be stopped before it is too late;.the cooling system must first be tested by a radiator shop to determine whether the head gasket is leaking. If the head gasket is leaking; the head must be removed and remachined; or else the car should be taken out of service and not driven until you can afford to fix it properly. If the head gasket is not leaking; the thermal fan switch must either be replaced; or the fan motor rewired so that the fan will run all the time when the key is on.
Jaguars are known to be far more expensive than non european cars to maintain. If you are unhappy about the costs of owning this type of car; perhaps it is time to reconsider whether it would be preferable to own a more economical vehicle. Such expenses are likely to continue as long as you own this car.