Having managed to persuade my employer to manage without me at the end of February (at the age of 58.5), I was able to find more time for cycling, despite other commitments. So I moved from essentially short commutes (maybe 25 miles/week total) to wind up to more like 120 miles/week over two or three months.
I was mainly riding on the flat (not all that easy to find around wher I live in Sheffield, UK), doing 20 or 30 miles at a time, without any luggage.
Towards the end of May, I got a bus from near where I live to Bayonne, in SW France, with the intention to cycle back to England. I wasn't sure exactly how far it was, or how many miles I'd be able to do each day, so couldn't really estimate how long it would take. I was guessing 5 or 6 weeks from Bayonne to Calais.
I was impressed with myself that I managed, with about 40lbs of luggage (including camping gear) an average of 54 miles (87km) every day for 14 days. Min 46 miles (74km), max 64 miles (104km). Average speed a little under 10mph. This was despite what I think of very high temperatures on some days - 33C/91.4F - way more than I'm used to in the UK. I camped every night excpet 3 (one stayed with friends, two hotels).
When the weather turned very wet and windy in northern France, I happened to be near Caen so I caught a ferry to Portsmouth rather than slog through thunderstorms to Calais.
Looking forward to the next journey.
More (including pictures) at donabif.blogspot.com