Are you joining direct LH? If so you should eclipse what you’re earning as FO/SFO at easyJet without too much bother from day one (Capt is a different story) even after the substantially better pay rise you’ve received there. (Another story altogether but well done to the easyJet CC compared to our lot).
The U2 figures I’ve seen I spat out my coffee at originally, however missed the fact that they included pension and sector pay etc.
By way of illustration my allowances in May are just a smidge under £4K. However it’s a pretty busy month and includes a couple of hours of NCP too. Going forward on average you’re looking at just under £3K in monthly allowances on top of basic so add £30-35K to the basic as a Long Haul FO at BA for your sums.