It'll be very interesting to compare notes.  Your numbers are similar to ours but a little larger.  Even the price is close like for like although we've had new radiators and pipework throughout.  

https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/my-ashp-installation

Did your installer think your radiators would be OK with the lower flow temps? This will be useful to others replacing existing systems, which I'm sure will become more a more common.

Good luck with the installation and keep us updated!

Sure. Your install looks tidy. It is quite difficult to get like for like comparisons because my quotes all had different solutions. 
my chap quoted £200-300 per radiator swapped. So that’s why I’m going to try without changes first. 50% of my radiators are single panels with fins. The other 50% are double panel, double fins. The only place I’m concerned about are the towel rails in the bathrooms. 
it will be interesting to compare the hot, cold & hot again of a cycling oil boiler to the constant background heat of an ASHP. Although the Daikin HT runs at a hotter temperature than a typical ASHP, I hope to turn it down a bit to save electric costs. We shall see. 

We found that swapping out heated towel rails for dedicated bathroom radiators made a huge difference as they actually give off heat instead of retaining the heat on a towel rail. 

Useful information George. Thanks

Our ASHP installation date is set for 20th April

The day of my oil boiler replacement with an ASHP approaches. Here is a photo of the boiler cupboard before any work. And my current OSO hot water tank. My installer will remove the oil boiler. Which I have sold on eBay. This will fund the removal of the oil tank. 
The oil tank is being removed by a different, registered company 

It will have to be drained (understandable) and then unfortunately cut up, as the company cannot crane it over the fence / hedge you see. 

I will next send photos of where the external unit will sit. Exciting 

@julianc, that's exciting indeed. The logistics of removing an oil tank must be a real headache, but it's great that everything is taking shape. 

10mm pipe drops to each radiator, from 28mm loft pipes.

This is quite interesting in light of our house - as it transpires, we may have 15mm pipes feeding our central heating, reducing to 10mm out the wall, and this is what is potentially responsible for poor flow rates to the rads in the coldest parts of the house. 

I am pleased that we have solved this issue (we will film an update video in a few day's time) by increasing the size of the circulation pump, upsized the rads to K3 units and balanced all the radiators. It's worked a treat.

On that note, have the installers recommended changing any rads as part of the heat emitter guide? 

Mars, they have recommended to change 5 or so I think. But they are in bedrooms, so we are thinking to try it and see. 
We use a Nest thermostat (which we will continue to use with the ASHP). Currently the Nest never goes above 19.5C. The heat loss & room temperatures were 21C for sitting room & dining room and 22C for the bathrooms. So I’m thinking we should also be ok with the ASHP temperature range

I also like George’s suggestion of swapping bathroom towel rails for radiators 

Interesting you should say that; we have 2 ensuites and a main bathroom.  The main bathroom has a towel rail and the ensuites one of each. It was all down to the heat loss calculations; the ensuite with the radiator is on the corner of the house and the towel rail we had space for wasn't enough.  The towel rails were enough in the others and they seem OK so far.   

Snap Kev M.  I will wait and see how things go. But of all our rooms, I do like a warm bathroom. 😊

In the meanwhile, this is where the outdoor unit will be located - roughly where the pallet is leaning.  Pipe work will go through the garage under the window. The hydro box will be located in the garage, behind where the external lamp is.  If you look carefully you can see the current oil boiler flue pipe and the electric meter cupboard beyond.  The oil boiler will the removed and replaced with a buffer tank and pump.

Oil boiler removed.

Buffer tank in here now. Hydro box installed in garage. Daikin and Mixergy delivered. Old oil boiler sold on eBay.  Oil tank drained and removed. Good day 1. More photos to follow