The most important part of any heat pump installation is to get an installer that is knowledgable and competent, and that will evaluate your property and install a well-designed system that will heat your home efficiently. This step is far more important than the brand of heat pump you choose.
We installed our heat pump in 2018, and it was a reasonable installation (it could have been better) and we share our personal tips and advice as homeowners on what you should be looking out for and what should be setting off red flags.
Renewable Heating Hub forums: https://renewableheatinghub.co.uk/forums
Heat loss calculators: https://renewableheatinghub.co.uk/forums/safety-regulations-tools-diy-installations/heat-loss-calculators-and-spread-sheets
MCS installer directory: https://mcscertified.com/find-an-installer