Guidance on a new bike

I’m looking to buy a full carbon road bike for long and fast(ish) days out, much of it on hilly terrain & dodgy tarmac around the peak district, but also the flat lands of Cheshire & annual trips to the Alps. I will not be racing, but will be pushing my aging legs around some longer sportives.

I’m 6 foot 2 inches (188cm), a little over 14 stone (90kg) and put a fair amount of power through the pedals, so I want a stiff frame and set of wheels good for cranking hard up short stiff hills as well as grinding up Cragg Vale and Holme moss.

My price range is £2000 to £3000 and after a lot of thought I have decided to go for hydraulic discs – reinforced by having just turned a set of nice rims into aluminium foil through prolonged breaking on long wet roads shared with tractors & their mud!

My very provisional short list is as below – all with Ultegra.
Giant Defy Advanced Pro 1
Cannondale Synapse
Scott Solace
Rose Xeon CDX – this is my current preference
… but I’m open to any suggestions – especially smaller companies.

Finally, I’m considering Ultegra Di2 – everything I read is positive, always perfect changes regardless of conditions, monthly or better charge cycles, etc. But what options are there if/when it goes wrong? How easy/expensive is it to get spare bits – presumably most LBSs are unlikely to have the parts – so if you’re on a few days trip what options are there?

Many thanks in advance for any suggestions/tips etc.

Kevin