Ahhh I see that's made from small blocks end on end and side to side, you could make it out of 2 or 3 planks joined side to side. With care in matching the colour and grain you'd hardly see it's not a single piece. Even better if you can get a thicker piece split so it's bookmatched,
Not knowing where you are in the UK I cant say, have a look round for small joinery shops or furniture makers. They could cut you a longer plank/ offcut to join up to the correct width and indeed run it in the thicknesser to get the correct size, you can get a router bit for cutting biscuit slots if you don't have access to a biscuit joiner.
Most small places will do it for a few beers tokens though, I know were I used to work we had loads of offcuts that would be perfect and most went for fire wood..