Electric combi boilers / solar panels / eco heating solutions

Bugger, I completely missed this (I ran a marathon at the beginning of the month and then got Covid so haven't been terribly attentive)

A few tl;dr observations/ brain splurge...

Electric heating bad. Very expensive to run and in the case of electric UFH a nightmare to repair or replace if there are problems.

Heatpumps good. Very good. There is no more efficient way to convert purchasable energy to heat energy than a heat pump installation and this narrative that's been doing the rounds in the media recently that "heat pumps are now cost comparable to boilers" is a load of shite. I've been installing HPs for the last fifteen years and in most instances you can expect a payback of 3-5 years. That's an actual payback as in the the amount of money you will have saved on running costs will have paid for cost of the installation.

Solar panels are good but you need to really know what you're doing with the spec and installation if you want to use solar thermal as a standalone heat source... it is possible but I'd rather have a HP myself and know that you'll have dependable heating and hot water all year around. Solar as an add on to HP is a great choice and I know Viessmann for example have been really focussed on allowing their controls integrate the systems to maximise efficiency which is very good.
EDIT: I'm referring to solar thermal, PV panels are great in most instances and make great sense with HP as you don't need to worry too much about storing your energy as electricity when you can pump it into heating and DHW, another argument in favour of a good size buffer tank...

If you are considering a HP and the installer says you don't need a buffer tank walk away, they're idiots. There are a number of reasons why your HP installation should have a buffer and not having one is a bad idea, also with buffers the bigger the better so if you have the space for a big one then get one, you'll reduce the number of starts on your compressors which will prolong the life expectancy of the machine and also allow you to maximise use of night rate electricity.

Wet underfloor heating is the best for heating distribution, there are also some very good capillary tube heating distribution systems available these days too. Radiators are ok with HP these days but it's certainly advisable to upgrade to more efficient aluminium radiators that will allow you to run a lower operating temperature.

As previously stated by others absolutely do go nuts with insulation where available and I also wouldn't rule out retrofit wet UFH in a lot of instances, it might cost a wedge at the moment but why not cool the jets on that fancy kitchen and then upgrade that in a few years when you've reaped the benefits of your efficient and cheap to run heating system... mechanical works are almost never something that's easy to upgrade down the line without major disturbance.

I'll try and answer any more specific questions people have if anyone wants to ask anything, I've been working in the HP industry for fifteen years and we've won a bunch of industry awards so I do know what I'm talking about for once...

I'm also currently upgrading our own flat with an air source heat pump installation, upgrading some of the radiators and also adding in some retrofitted UFH in the bathroom so it really is all achievable and I'd even argue there are a fair few elements that a competent DIYer can do to keep costs manageable.

:)