It's highly unlikely that a mortgage company will lend you more money when you are BR. Once you are discharged you will probably still have problems getting a higher mortgage for a couple of years.
Are you suggesting that you have equity and you could look tio secure additional borrowing from your lender to avoid BR?
That MAY be an option - if you are able to demonstrate that you have the income to support an additional loan. I am assuming you have non secured revolving creadit debts - if so, that will be a possible barrier to topping up a secured mortgage.
Do not look at other forms of secure borrowing - i.e. a second charge - they are often burdonsome and may cause you more problems.
Take some advice before looking at options - you must do that anyway before petitioning for BR