I revoked on trick 11 and the trick was played out. On trick 12 I was second to play and the revoke was pointed out. I was told to correct the revoke and we would sort it out at the end. I won the last trick. I know we did not proceed correctly but should I have been penalised?
The penalty for an established revoke, as this was, is one trick plus return of the revoke trick itself if you won that. So you would properly have forfeited the 13th trick, plus possibly the 11th trick under the condition above.
There is also a provision for the Director to assess an additional penalty if required to restore equity. It is unlikely that such a circumstance could arise on the 11th trick.
If you had not yet played to trick 12, then you acted correctly in correcting the revoke and continuing on. If you were defender, there may have been additional penalties in terms of your incorrectly played card becoming a penalty card (depending on the situation).
If you had already played to trick 12, then the revoke became established. An established revoke is not corrected, ACBL Laws of Duplicate Bridge Rule 63B:
Revoke May Not Be Corrected
Once a revoke is established, it may no longer be corrected (except as provided in Law 62D for a revoke on the twelfth trick), and the trick on which the revoke occurred stands as played.
As such, you should not have gone back and corrected trick 11, but instead played the final two tricks and then been penalized (one trick, plus the trick you revoked on if you won it, in most cases).
If an opponent instructed you to correct it, then I would interpret that as agreement to treat it like an not-established revoke; in a casual or even club setting I would typically allow a novice player to do so even if the revoke had been established. However, I would not then expect any further correction or penalty to be applied (and would be perfectly willing to let them treat it like an established revoke). This is also not explicitly allowed by the rules, so I would certainly not do so in a competitive setting beyond regular club level.