As the title implies, is it possible to send your own mares to your own stallion, if so, would someone be kind enough to explain to a numpty like myself how you do this, for the life of me I can't find it in game.

Thanks, much appreciated.

Yes you can send your own mares to your own stallion.

1) go to the my breeding tab
2) there should be a list of your mares select one by clicking the small “s” in a pick box at the very end column, then it should turn from pink to red. Your mare that you’ve selected should come up in a box at the top of the screen.
3) scroll down the AI sires page to find your own stallion click the small box with the “s” in again. I think it’s after the stud where there stallion is standing. That box should turn red with a white “s” in as before. The stallion should shoe at the top of the page like your mare
4) at the top of the page where your mare and stallion is press “confirm”

You can sort the international sires list alphabetically, and rename your own sire barn (once you buy the stud barn part).

I find it useful to name my sire barn starting with A or W,X,Y. Then I can touch sort on the stands at field and get my sires to pop to the top when I want. Old hands are anti-scrolling!