Anti-English setup

In the reversed closed sicilian line suggested by the OP's teacher, giving up the centre with 9...e5xd4 doesn't look very natural. Don't think d4xe5 is a threat is it? Otherwise looks a reasonable line.

For an inexperienced player would recommend just putting a pawn in the center,and developing with 1.c4 e6 2Nf3 d5 3g3 nf6 4Bg2 Be7 5.0.0 0.0. It isn't bad at top levels either. Michael Adams recently used it to win against one of his main rivals at British Championship.

The opening you suggested is not really a Grünfeld. It's only Grünfeld if white has a knight on c3, unless white has played g3 or Bd2, when placing the d5 knight on b6 is justified. The line 1.c4 g6 2.d4 d5? 3.cxd5 Nf6 4.Nf3 Nxd5 5.e4 is a transposition into the Marshall-opening, which is just awful for black. It comes down to playing the line 1.d4 Nf6 2.c4 g6 3.Nf3 Bg7 4.Nc3 d5 5.Bd2 down a full tempo.

If you want to play a Grünfeld setup against 1.c4, you have to start 1...Nf6. After 1.c4 g6 2.Nc3 Nf6 3.e4 it's going to be a King's Indian defense.

Obviously, except in case of 1.c4 Nf6 2. Nc3 d5, in which case Black can take the knight on c3.

True, that's a possibility. But here white has some good extra options due to not having played d4 yet.

And besides, white can play 2.e4 immediately.

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I messed the line up but he reccomended a closed sicillian

Reversed Closed Sicilian is in fact one of the most reliable setups against the g3 English.  I also like the variation 1.c4 e5 2.Nc3 Nf6 3.g3 c6! (Reversed c3-Sicilian)  It is a bit more aggressive, and Black needs to know what to do in the case of 4.Bg2 (allowing Black to occupy the center with ...d5) and 4.d4 (where 4...exd4 5.Qxd4 Na6 is a good way to play)

@TwoMove:

dxe5 is a threat. As illustration have a look at: https://www.chess.com/games/view/13224840

These kind of endgames are horrible for black, because of the bad pawn structure, bad light-squared bishop and lack of any play. The statistics in the chess.com database clearly favor white +4 =5 -1. The black win being due to white paying a completely wrong plan.

You do have similar structures and lines in the Leningrad Dutch, especially Avrukh's d4 repertoire suggestion for white leads to the same pawn strucure and he claims a clear long lasting plus for white.

There are many good ways to play against the English.  The challenge is NOT finding the "best" according to some computer program, but finding one you understand, like, and can handle in practice.

Hi zeitnotakrobat, the OP showed a line were white delayed d4 for a move, and black has castled, so the endgame would be easier, I guess. Anyway white can play d4 earlier, and even there the endgame doesn't look so terrible to me, black does have two bishops. For example a game of Carlsen reached the position as black, and the opponent chose b4 instead of d4xe5

After 1.c4 e5 2.Nc3 Nf6 3.g3, I think the early nc3 doesn't go well with g3, and something like 3...Bb4 4Bg2 0.0 50.0 Re8 good for black. Delchev looks at 3...c6 but after 4d4 exd4 5Qd4 suggests playing the IQP after 5...d5

@TwoMove,yes castling first for both sides makes black's life easier, but is less accurate for white.

After dxe5 you can of course take with the knight, but in that position black would probably like to play f5 back to f7.

The problem in that type of endgame is the light-squared bishop. It has nowhere useful to go. On the queenside it is blocked by the white pawns and on the kingside by the pawn on f5 and once white manages to go f4 that bishop is miserable for the rest of the game. White also plans to go Nc3-a4-c5 taking away even more squares from the bishop.

The dark squared bishop can probably be traded by putting pressure on black's e5-pawn.

Anyway, I played endgames of that type in rapid tournaments and lost the black position without any chance to 2 IMs, whereas with the white side beating an FM also without trouble. In all of these games things went along the course of the game I linked in the previous post.

Btw, b4 is recommended if black goes e4 after d4.