The trains aren't bullet trains. We are just living in the 2000s. There are a handful of high speed trains in India but their max speed is 160km/h.

Theoretically it could be done in 11 and a half hours, but practically the train doesn't always go at top speed and there are stops along the way so more realistically something like 13 and a half to 14 hours. Perhaps a little more if there are delays here and there.

Edit: this was assuming that the track goes in a straight line as the plane flies, in reality the distance the track covers would be slightly longer just like when you're driving, so add another 10%. It's still much faster than driving and way less stressful than flying.

About the same as a plane if it was a direct next gen maglev.

There are tunnels going underneath the water between mainland Europe and England. The Channel Tunnel for railway is 50km long which by train takes up to maybe 15 minutes I think.

England is not an island. It's a myth. The rest of Europe just didn't want to be associated with it, so they all pretend that continental Europeans can't just walk over. England goes along with it because it's racist. There was an old English king who was fed up with wars with France, who started the myth to see if it stopped his french cousins from claiming the crown. This is also why there's a big white stripe down the middle of the French tricolour: it represents the white cliffs of Dover Calais but most people have forgotten. The channel is essentially a big puddle but only around the edges. All those ships are flat at the bottom with wheels on them. That's why the French call it the sleeve; it's deep enough in places that an average sized adult might get their sleeves wet if they did try to walk across some parts. The story was so successful that the Spanish launched an armada not knowing that their ships with round bottoms would flounder as they got close to England and they all hit the rocks under the water and so never made it.