13000 isn't going to get you a lot in long haul. You need to add a zero to that.
And remember the 'Cabin Upgrade' is not really a cabin upgrade, it's a reduction in the Avios needed for a reward to the class below what you book. You can't book into F and unlike Amex there is no additional reward availability, so if you want J or W you will need those reward spaces to be available to book (and pay W or Y Avios for them, but the taxes for the flown class).
So the cabin upgrade is just worth the Avios you would save on whatever redemption you planned. That *could* be the equivalent of about £400 but it could also be much less. You will struggle to get full value out of it every year with your flying patterns as it only works on Avios redemptions not cash bookings and you won't have enough Avios to spend enough on each journey to make the reduction significant.