Average age is 55 apparently. Which is what I'll be next year. Hence my interest.
As Andy says, I don't think it's something you do to 'enjoy' - a sense of achievement perhaps, but not pleasure.
I think as Ppp says above, four and a half long days would probably do it. Tim and I did a 300 mile / 26 hour first day, grabbed 6 hours sleep, then completed it with a 175 mile / 16 hour (almost) daylight session. If we'd spent 8 hours resting in Edinburgh before starting the return trip, we'd still have had an additional 8 hours in the 'bank' to spend resting on the way back.
If I were doing it again, I'd do 200 miles, then get some sleep before tackling the Howardian Hills around Castle Howard with fresher legs. Of course timing sleep sessions with sleep places needs some planning and good fortune.
In terms of recovery, my legs could have turned the pedals of my bike yesterday again, but I'm not sure my backside could have coped. In fact, I'm still saddle sore today. So you need to be really sure about your saddle. Which I guess means getting the miles in between now and then on the bike / saddle you plan to use for LEL. I hadn't used my Thorn / Brooks combination for any serious distance since the Lands End to London leg of LE-LON-JOG earlier in the summer, other than for the FNRttC/SMRbtH a few days before. Clearly that was a mistake!
There are some stunning stretches to be cycled along the route. Around Castle Howard, around Barnard Castle, the Pennines, north of Moffat to name a few. But there are also some tedious stretches - The Fens and the road north of Gretna ( the old A74 I think) are examples.
As I said in my post above, proper food and proper hydration needs careful management. I got that seriously wrong.
In fact. Planning is the watch word. This is not just another ride, it's a serious undertaking and will require a lot of prep.
At the moment, I'm inclined not to enter LEL13. However, as Mrs rb58 said when she was mopping my brow, it could be (a bit) like having a baby...... At the time you swear you're not going to go through it again, but time heals and you end up remembering the good bits. (of course, I know riding a bike is not in the same pain league as having a baby, but you get my drift).