Scruff:
700c audax road bikes are designed for doing long days, big miles at decent pace.
They’re generally quicker & lighter than tourers with a slightly more ‘focussed’ feel, but nowhere near as ‘committed’ as a full-on road/race bike.
Mudguards usually come as standard and racks can always be P-clipped if no fittings are brazed on.
You should be able to pick up something 2nd hand for £300… (search for any road bike that comes with full length fitted mudguards).
You could get a Dolan build (as suggested above) a Tifosi or a Ribble winter/audax for about £600 if you want to buy new.
Steer clear of anything with a 53/39 chainset (gearing won’t be fun on hills with luggage).
Get something with decent puncture proof tyres (25-28 width).
Comfy seat (brooks/spoon type).
Buy the best frame you can afford – a good audax is a very versatile bike that will see you through crazy miles of commuting, club runs, sportives, alps trips, light touring!
A decent set of handbuilt wheels on a good frame can be paired up with some basic running gear like Shimano Sora or Campag Mirage (bought off here).
The below is from SPA cycles looks great if you have a bigger budget: Ti frame with sensible build and even decent tyres for £1500.
spa cycles – ti audax