Certainly from UK out across most of EU, your CBF would do fine (mostly!). It's really up to you how much back road/bad road or OFF road you travel. Mostly, it's all paved, but if you go "exploring", you can get off road a bit and find some interesting alternative routes.

My question relates to getting through some of the countries along the way.
Whether coming to India via the Stans, Pakistan, Afganistan or through Iran or Syria, it's a challenge getting to India overland.

I would imagine you'll encounter a lot of "bad road" but mostly a road of some kind, maybe dirt but probably all season, passable on your CBF if taken at moderate pace. If muddy or wet? Who knows? I have been turned around on my street bikes a few times on muddy roads. Even a dual sport can be stopped.

If riding dirt roads/Off road or bad roads at speed, ground clearance can be an issue. The CBF's short travel suspension may bottom out carrying a load. Sub frame can crack or bend, chain can get stretched, riding wash board stuff can vibrate loose or work harden and snap.

Maybe do a long shake down ride around rural Ireland? Lot of "bad roads" there, tight, narrow, drivers keep a suicide pace. Ride those Irish roads fast and survive, I'd say you can make it to India ... with a bit of luck.

Getting through Pakistan, Iran or other war zone countries ... well ... that's another story.

I've traveled a bit on road bikes doing all sorts of "bad" roads. Across USA and Canada several times, Mexico, EU. Rode everything from Vespas to Honda 50 step throughs to 1000cc Vstrom, to Triumph Tigers, various Ninjas and more.

Favorite travel bikes by far are 650 class dual sport bikes. I've owned a few: XL600R (Dominator), XR650L, KLR650 and current DR650 Suzuki. The Suzuki is by far the best of the bunch (for me). After 65,000 miles on the DR650 and about 100,000 combined miles on the others, I like the DR650 best.

Pot holes? Topes (speed humps)? I don't even slow down. Fast highway? I can cruise at 75 mph 10 hours a day. Deep sand on loaded bike? Doable with some skills/practice. Bad Roads? What bad roads? I don't even notice.

Don't worry about your off road riding abilities. You will get better with practice.
It will be TOUGH at first but you will learn. A lighter, more off road capable bike allows your learning curve to accelerate ... and is generally SAFER for the rider as you will crash less. Crashing sucks!
Good luck, rubber side down!