My car requires a new head gasket, what should be in the HG set ?

9 months ago I paid a garage £950 after they charged for head gasket ( found out later they only did Waterpump). Last week I got a chemical test done for my car, changed color instantly indicating bad HG.

Car runs fine, no oil/water mixing, no smoke, just loosing water

Went back to said garage to inform them hoping they would offer a solution, but they didn't.

My friend who is a qualified master mechanic (runs his own business repairing cars at home ) said he could replace HG for me for £400 including parts ( but I would have to pay extra £30 for H skim ) I asked him if he would be replacing valve stem oil seals but he said no, said it was a bit of a job in itself and besides , my car does not smoke whatsoever so he says we will re use VS seals.

So I will just pay him £400 and he will provide the parts, I don't really want to keep asking him too many questions such as asking him what parts he will buy and fit because I don't want him thinking that I am testing him. At the same time I need to know what he is going to be replacing with HG so I will ask him when I see him next.

My question is, what is in a Head gasket set only ( not timing belt set, he will be doing that too but I am just asking what should come in a HG set and how long on my car type do you think it should take to replace the HG ??

Thank you

My car is a 2006 mk2 focus 1.8 TDCI Sport

( it's already had £1500 on this car and several thousands repairing previous cars)