Cycle Touring in India

I'll be using my singular peregrine with my 29er wheelset and 1.35 hardpack tyres. I'm planning on running it in a 1x6 set up with a 38T chainring and a 14-34 cassette. Luggage wise I was hoping to take two medium sized rear panniers and a bar bag.

To test the setup I'll probably do a 3/4 day domestic tour in July. London to Bolton crossing the peak district, luckily I have friends/family at 60ish mile intervals on the route.

My friend will be buying or borrowing a bike so not sure yet, but it'll be a similar set up albeit with more gears.

That sounds like a good choice - a lot lighter than what I toured on which is quite enviable, but then I think you'll have much better roads in the South. Only possible problem I can think of is that you'll only be able to get 26" wheel spares out there, so carry plenty of inner tubes, spokes and maybe even a spare tyre. But then in 3 weeks you're unlikely to have anything major go wrong.
I carried far more luggage than I should have really - mainly because I took a heavy slr camera as I knew it'd help keep me sane when not cycling.

My bike testing and training ended up being little more than one ride down to Brighton in the end - which was really stupid when i had several months to prepare.