Generally speaking, I agree it's never a good idea to have a referendum on something without having a very clear picture of what a "yes" or "no" vote means. Without that, it's inevitable that discussions arise about how the outcome should be interpreted. In your case, amongst other things, the hard vs soft brexit debate.
On the other hand how could your government have presented something concrete to vote on? Negotiate with Brussels first? They'd go for the worst possible deal to ensure it would be rejected in a referendum. From that perspective you're arguably better off starting negotiations with all parties knowing the deal will go through as agreed.
It's possible the current murky process will actually yield the optimal result for you, yet many who voted 'leave' will hate it and revile politics for it.