No replies? You must be feeling like Billy no mates.
This is what I would do.
Drain the rad and block, take out the stat and use the garden hose to flush the engine block and heater matrix separately.
Remove the rad, flush inside and clean the outside with the hose giving it a good shake to remove deposits.
Flush out and check the small hoses going to the expansion vessel.
Put it all back together replacing any deteriorated hoses and clips and a new stat.
Refill will 50% new antifreeze 50 % de-ionised water.
For the antifreeze, I use Comma oils, put your reg and post code into their website and it tells you what fluid to put in and a local supplier - I've used their fluids for 30 Years and found them to be amongst the best and reasonable priced.
Get the de-ionised from your local supermarket.
If the waterways look bad then use a flushing agent, again use Comma for that. If I used a chemical I would do 2 flushes with a hose, one before and one after, (make sure the stats out when flushing to get a good flow)
Hope this helps.