Due to fly long haul on Tuesday, but stuff happening at home means I need to cancel. Insurance probably won't pay out, so looking at options.
If I cancel on Manage My Booking it seems I commit to an unknown calculation that BA will make with no comebacks - I'm assuming that will amount to a return of the taxes fees and charges and perhaps a service fee - does that sound right?
In Manage My booking it says "It's not possible to make changes to this booking online. Please get in touch with your British Airways Customer Services team for further assistance."
Before I start phone tag hell, what are they likely to be able to do - is there any possibility of more money back, a voucher for future spend, or the possibility of rearranging flights?

Or do my circumstances consign me to losing circa 60% of the money I spent?

Many thanks as ever for the considerations of the forum.