If you want as light a bike as possible as you have the all weather option covered, a carbon bike makes sense.
Whereabouts are you in the country, as
Ribble, Dolan etc as well as LBS like Paul's or
Rutland cycles can have some v good end of line deals
E.g. giant Defy with Ultegra for £750
https://www.paulscycles.co.uk/m7b0s6p6992/GIANT-DEFY-0-2016
Or Cube carbon with Ultegra for a grand
https://www.paulscycles.co.uk/m7b0s6p6694/CUBE-ATTAIN-GTC-RACE-2016
That said, if local and the right size, this is gorgeous and a bargain, the frame alone sells for around £600
https://www.cyclechat.net/threads/kinesis-racelight-aithein-50cm-for-sale.217067/#post-4771146