Well,
I flushed the old coolant out and fitted the new expansion tank and cap. When I was flushing the system out I noticed the water hose, the block to oil cooler one was split at the bottom. After purchasing a new one from ebay I finally connected everything back up yesterday.
I replenished the coolant system using Comma G48 (G11 spec) using a 50/50 mix with de-ionised water.
The fan kicked in and all the hoses at the top and bottom of the radiator were at the correct temperature at the correct times. So I was happy. No thermostat issues.
Last night I took the car out for a drive.
The temp gauge was sitting just past the LED. I was not thrashing it or driving it hard, although the occasional drop to third and spirited drive did happen

No lights came on. So was happy. I checked the coolant levels on return and all were ok, albeit engine still warm. I checked them this morning engine cold and still ok.
HOWEVER, On closer inspection I have noticed a light leak from the cylinder head gasket area on the right hand side of the block. I wiped this and watched and waited. Sure enough another drop formed after wiping it away with a rag, and then shortly after another.
It would appear I have cylinder head gasket trouble. Or at least that is my judgement.
Looking for some advice here. I have a few questions.
The engine has no other symptoms of head gasket failure. I know people always bang on about "mayo" formation and I have been one of them. No engine oil consumption or other signs of head gasket failure other than leak from block area. No steam or anything like that. Rather annoyed I never spotted this earlier.
I am reasonably mechanically able, but have never tackled a cylinder head gasket change. Only ever small jobs How much would a decent garage charge for this?
Realistically would the engine need to come out. Would it be worth my while skimming the head?
Should I tackle this myself and if so what price? Also what other jobs would be good to get done whilst this was happening? Water pump etc. I work two weeks on/off. So from Tuesday I will be away. So wont be able to progress with the car

Any and all advice much appreciated.
Cheers.