As mentioned unless you need the AC wifi & better possible feature, to me (i am not in UK any more, but i don't think it matters as using adsl annex A) the latest broadcom chipsets are not so stable their firmwares with adsl
My line seems suffers from REIN because several telephone poles are together with electricity cables (now if is illegal or not this is an other story) ...
I have the zyxel vgm 1312 (BCM63168) and while the snr target is stable (not drops) when there are sudden errors burst (from time to time) is amount of time when will be disconnection ... other modems chipsets (draytek, asus) are keeping the line way better (no disconnections, maybe once a week i reboot manually because are millions of errors)
With the zyxel everything started with firmware VMG1312-B10A_1.00(AAJZ.4)C0 & later (beofre was fine) ... seems they have focus with vdsl in their firmware & have forgotten adsl with latest firmwares
Other older broadcom supporting only adsl are fine (billion 7800, 7700 / tp link 8960v5 / dgn2200v3 which i own)
EDIT ... & note i am at broadcom exxchange (appearing as BDCM:0xa3a7) where should match algorithms and should be better (as other brand models)