Tottington through to Fulking is a nice route, very tempting to carry on to The Beacon, though.
Which I wouldn't do, nice to have a challenging surprise.
(I've just put a Bikely route, onto the post you have just quoted).
That does seem a little excessive for L2B, for an average bloke.
But I totally agree, if you can do 30 you can do 50 miles, no probs, esp on a friendly circuit.
I'd image your commute will be enough training, as the L2B really isn't to taxing.
A nice little loop round for a Sunday morning...
Do you start work at 9?, and do you drive or train?
I used to drive a similar distance along the coast, for 9am.
It was approx 20-30mins quicker to ride.
Deffo get the tyres sorted before you start, as there's no enjoyment otherwise.
But be prepared you might actually take to it, which will...
There is a reason why everybody says TYRES.
So change your tyres.
Lock the suspension.
Eat and drink well, depending on how long you think you'll be.
There are plenty of food stops en route.
Start as early as possible. Or else the bottle necks and Ditchling will have you doing a lot of walking...