If you have some knowledge and used to doing some of your own auto work, flushing and back flushing is a relatively easy and straightforward operation. As for bleeding the system, that's a real easy doddle, there are many posts on the forum telling you the best way to bleed the cooling system. Believe me, both of these operations are pretty easy to do and your won't require an expensive visit to a mechanics workshop. All you need is a few tools and access to a water hose.

Personally, I would start with bleeding the system to expel all of the air, it costs nothing if you do it yourself and then if it doesn't solve your problem look into flushing and back flushing the system. If that doesn't achieve what you need, only then start down the thermostat replacement route. When you do these ops don't fill with anti-freeze and inhibitor until you have sorted out your issues and only then fill it with anti-freeze otherwise you'll be throwing away money on it. If the weather is freezing don't leave the coolant system filled without antifreeze overnight though. If you do use anti-freeze and need to drain the system after you have filled it recover the anti-freeze in a bucket or bowl and reuse it again but filter out any crud through and muslin or paper filter. Hope it goes OK.

Always start with the easiest and cheapest solutions first as it costs less in time and cash.

This might help you a bit: http://forums.lr4x4.com/index.php?showtopic=48416

https://landroverforums.com/forum/se...archid=1252744 some of these will answer your questions although there's some reading to do!!

 

The post right above this one, I gave a link to bleeding. Here it is again:
https://landroverforums.com/forum/di...51/#post353088