I placed an order today at Screwfix but was surprised to that they had
no sanding sheets in 280mm lengths as thats what my Wickes sander uses
.. All the 1/2 sheets they have are 230mm .
I know they are available as other sites have them

The sander is the kind with punched holes for the dust in the plate
and the clamps and levers to secure the sheets .I've never been
entirely happy with that arrangement as I have found the paper isn't
held securely enough and tends to slip.

The base of the sander is a rubber piece .I was wondering if it might
be feasable to get a sheet of Velcro and stick it on to the rubber
( putting holes in it might be a problem tho') and utilise the hook 'n
loop sheets ...they are probably more expensive tho'.