head gasket

First of all you didn't say what the symptoms or problems are so it's impossible to know why someone recommended a different engine. Second, head gaskets are commonly replaced. You do not need a different engine that is likely to develop the same problem. It is also customary to get a used engine from a salvage yard, not a new one from the manufacturer. I can't imagine why someone would try to sell you an entire engine if just the head gasket is bad unless something catastrophic happened. If coolant leaked into the engine oil, flushing the oil after replacing the head gasket is all that's needed, however by letting it sit for a long time antifreeze will melt the first layer of metal on the engine bearings. That WOULD get real expensive. You'd avoid that by getting the coolant drained out of the oil right away. You need to get a second opinion and you need to describe the symptoms so we know why they recommended a different engine.

Hi, really late reply i know but i seem to be sent in circles by the garage that has my car and as i dont have anywhere to keep it off road i have had to leave it with them. All i was told was that the head gasket had blown and there was a problem with the timing chain but when i had it i had just had a complete service at a local garage. After a week or so it was difficult to start but i put it down to the cold weather and not being technically savvy to follow it up. After reading up on the signs of a head gasket going i should have know something serious was wrong, the need to top up with coolant more than once should have given it away!!!
When it was picked up by the garage they manage to drive it back to theres eventhough it cut out a few times. I havent seen my car since!!! Its been a nightmare but they have been moving it to different sites and still telling me it needs a new engine. They have given me an old car to use (which im grateful for as i wouldnt be able to get to work), but as im still paying for my car i would like to fix it, finance is a huge concern and i have now gone full time in work to try and save up the a possible huge bill. I am fed up at myself for not knowing the signs earlier and annoyed that i have been taken advantage of : (

Nothing you've said so far really indicates you've been taken advantage of. I think there are things getting lost in translation and I suspect your mechanic is just as frustrated at the circumstances as you are. On many engines a problem with the timing belt or chain can result in bent valves which can get expensive but it's still a common repair that doesn't require replacement of the entire engine. That's why I'd want to know more about what they found and why they want to replace the engine.