It really depends on a number of factors.
The court will consider Section 25 of the Matrimonial Causes Act 1973 when it assesses a financial settlement. Therefore your ages, length of marriage, any children under 18, your earnings and earning potential (same for your ex), the assets including the former matrimonial home and pensions if applicable, any debts, financial and non-financial contributions to the marriage, your standard of living enjoyed before the marriage breakdown, your financial needs in future and your housing needs, and so on.
The starting point is 50% but if there is a disparity in earnings or you have paid more in the way of mortgage/rent, etc, you can ask for more than 50% of the former matrimonial home. It would be worth speaking with him to see if he would agree to any split.
If no agreement is forthcoming then you can apply for a judicial separation and apply for a financial order. It would mean you remain married and you wouldn't have to prove the marriage has irretrievably broken down (unlike for a divorce). You should certainly ask for more than 50% for negotiation purposes and especially if he has a good income and so on.
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