If your PCB material is thick enough, you can use a straight through hole connector as edge mounted. I've seen people do this before. Half of the pins on one side of the board, other half on the other side.
But it has pins like a standard PCB TH female header. I used one for a DIY USB blaster.
As dirtylude said, its just mounted as end launch, which is often done with 2.54mm double headers. If you do'nt require polarisation, then a standard 2x10 female header fomr Rapid will do just fine. However, if you're after one thats exactly like an IDC cable mounted socket, with centre tab, then a quick search on Farnell, and I got these:
As you're in the UK (I'm a fan of your shop btw) I would highly recommend Toby Electronics for connectors. They're reliable, you can order small or massive quantities, and they have literally everything.
I believe you're after these:
**broken link removed**