Wood To Strengthen Bookcase (PL4)

I'm in need of a piece of wood/timber to use to both cover up and brace the bottom part of a bookcase which I'm trying to strengthen.

The colour of the bookcase is a dark brown but since it won't be seen once it's been put in place it doesn't particularly matter what colour the piece of wood is I'll be happy with whatever I can get.

Minimum dimensions:
Length 120cm
Width 26cm
Thickness ideally no less than 2cm.

If anyone has anything suitable which they can spare I'd be very grateful.

I'm in PL4 Greenbank I can come to collect the wood as long as your address isn't too far away.

Thanks.