UKH

Looking around the £1000 mark for a road bike suitable for 30 minute daily commutes and 3/4 hour weekend rides.

Boardman 8.9 SLR from Halfords

Planet X Holdsworth Corsa

Specialized Allez E4

I have no idea what would select one over the other, anyone here got experience of any of these?

I'd opt for the Boardman simply because i think Shimano 105 is awesome (planet X spec SRAM on theirs and I've heard to many issues with durability)

I'd probably go Boardman too. They have a pretty good reputation for excellent value and I like Shimano over SRAM.

Either the boardman or the triban/van rysel you haven't listed  

Boardman looks good and 105 is good kit.

Only thing I'd consider is that the Holdsworth has disk brakes - if you're planning on using it all year round, it'll save wearing your rims out in the winter crud.