Too far south for my liking because:
1) from an IMBY perspective, it's too far south! Which is frustrating because the event we just had was too far north for me (by about 40 miles)...
2) from the UK perspective as a whole, the story so far this winter has been to underestimate the strength of the block, and correct those undercutting lows to head further south than they are originally progged. Any further south on that chart and it will be a great chart if you live in northern France
That said, taking into consideration the total size of the low/setup, such changes north or south really are miniscule in % terms. All we can tell this far out is that it looks likely there'll be another atlantic attempt at a breakdown towards the end of the week, and it looks as if it will result in an undercut of sorts. The broad position won't be known for maybe another 72 hours or so, and then maybe 96 hours before getting the "north or south of the m4 corridor" question answered, then I'm sure there'll be plenty of nowcasting at +120 hours; these set ups are notoriously difficult to pin down...
One thing that is more certain though is that there'll be some serious cold embedded over the UK through this week, which would be incredibly cold even for mid winter - let alone late March. This cold shoul, make any frontal snowfall somewhat less marginal than the one we just experienced.