How feasible is it to do this whilst:
1) having a variety of audax events around the country (I tend to travel outside my local area)
2) doing 20 events a year (including all distances)
3) holding down a full time job with a traditional working pattern
I've never driven. I used to catch trains to and from events but got extremely cheesed off with it. I used a train for the Invicta 600 and to get home from El Supremos 600 (I think) and the Wu'ze 400. It reminded me how much I dislike waiting at train stations and all of the hassle that goes with travelling by train with a bike. And they were quite smooth journeys. It's expensive too, but I am a tight git.
20 events in a season is
quite a lot.
Do they have to be calendar events?
I'd concentrate on the long rides as far as travelling goes. Do the 2 and 300k rides closeto home. Local events that you can cycle to and from before and after, even if you need an overnight stay before a leisurely ride home on the Sunday. Or do a DIY or local permanent. Start a thread on YACF and drum up some company. Permanents don't have to be ridden alone.
Then you can use up holiday from work to travel to and from the bigger events. The 600s in summer are much more worth travelling to than just an early season 200 IMO. Make more of an occasion of it. Much better to have a relaxing Friday cycling a leisurely 100 miles to an event and being all prepared than rushing around. Then take the Monday off for an easy ride home. It's no fun being at work when you're knackerred. But cycling home is good if you're not in a rush. You can stop where you like, have a doze or some coffee. It doesn't matter if it takes all day to cycle the 100 miles home if you're not in a hurry. I always enjoy my ride home from the Mersey 24, even though my legs are always stiff and it's a grotty ride down the A5. I just chill out and listen to the radio and take my time.
You could even do a week with events at each weekend and the midweek as a tour inbetween events.
but bearing in mind I don't have the mindset of riding through the night to do events and riding back.
Ever tried it? If you're well up on your sleep and not falling asleep on the ride and it's a nice night, it can sometimes be more fun than the event itself.
If you finish work early on Friday, you could probably manage a quick 100 miles before dark in summer?
Even with my 1600 finish, I've just about managed 100 miles just about in daylight in midsummer.