We own a house & property but due to circumstances beyond…

You won't be able to sell the property unless the caveat is removed and the mortgagee approves the sale.

Legally, as the mortgagee has the first entitlement to the funds from the property, the money lender's interest in maintaining the caveat is only to ensure that they are paid out of the sale price, any amount which exceeds the mortgage. So it should be possible to enter an agreement with them whereby you agree that on the sale of the property, all money in excess of the mortgage is applied to them, in exchange for them lifting the caveat.

If you don't want to enter such an agreement, because you want to keep any balance, then you will either have to persuade them to lift the caveat some other way, or challenge the legality of the caveat.

Your prospects of challenging the caveat will depend on the terms of your original agreement, and the circumstances surrounding your breach of the original agreement with the money lender, and inevitably, you will need to fully brief a lawyer to explore this option.

Your final alternative is to consider simply going bankrupt, which means letting the bank foreclose, having a bankruptcy on your record and starting again financially in three or so years when the bankruptcy period expires.

I trust the above assists your understanding.