He said he's got 10k to spend on boiler, UFH and laminate - that's fairly healthy just for that element of the works, obvioulsy that will change if he does the job properly.
He's also said that this will be their forever home - that's a signicant statement - they will be paying energy bills forever.
What's the point of throwing in a cheap to install, cripplingly expensive to run heating system now - you only pay for a proper job the once, you'll be paying energy bills forever.
You are correct, it is the OPs money not ours to spend for him.
So what budget will he need for the rest of the work needed even an expensive installation could have high running costs
The problem as I see it is that little thought has been put into the on going costs of running the system, this really needs a bit more than beer mat planning and a wet finger in the air to find a cost effective solution to provide heating and hot water at an affordable cost.
I've seen it many times where people have jumped in with both feet only to find their chosen system is too expensive to run with no access to mains gas and the possible planning issues with utilising alternative energy sources this property is going to be an interesting design challenge for someone