2 or 3 times a week - 22K/each way commute (flat)
Every other week 200K ride
Every week club run 80-120K medium group 28kph avg.
Two 200s a month PLUS fast club runs? Okaaaay... well, these alone are more than adequate to see you toward to the front half of most audax fields - if you end up a full value rider, it won't be down to lack of build-up!
Concentrate on other things such as Control Discipline; being fast on the road is wasted effort if you're dicking about playing the "Empty and refill the bag" game at every cafe. Remember to take your bottle(s) in for filling when you go, if possible get them filled by someone else whilst you eat; that kind of thing.
Once you get into overnight riding, work out what works for you. Ride with others if it makes you faster, learn if you need sleep or not. Really - the only way to find out what works is to JFDI and see; so do more than one 400/600 if you can, so there are fewer surprises on the 1000.
Work out what food works for you. Eating during the night of a 400, or next day on a 600 can be a challenge for some - more than once I've ended up unable to eat with 150km still to go, and it's unpleasant. I've worked out a solution that works for me, but yours will vary.
Hills are about power:weight. You can be heavyset and still be a decent climber if you're powerful, but remember - that power needs to be fed, and if you're having eating problems, you'll suffer in the hills if you're more anaerobic when climbing. The advantage that lighter riders have is that climbing has less impact, and requires less fuel.
