Mark, Ashley , welcome to Redsquare , you have bought yourself a pretty rare to UK Commando 7 , but don't panic about it being rare you can find part here in UK fairly easy , the commando 7 is pretty much exactly the same as the commando 8 only engine sizes are different but most parts will fit both tractors .
This project will be a wonderful bonding journey for you both and will be thoroughly enjoyable . You may wish to join our sister website !,, myoldmacine.com where you will find quite a few Wheelhorse owners based in UK and also USA . Both Redsquare & My old machine will be your best Wheelhorse manual that you will ever have, also you can download your tractor manual from here .
One word of warning ,,,,,,,, this hobby is addictive and trust me you will end up owning one or two more tractors in the near future , I just hope you have a strong marriage as your wife MAY become a Wheelhorse widow .
i am based not too far from you here in Somerset and I started out with the same tractor as you and have been on an incredible journey with this hobby and have met some awesome people , I now currently own around twenty 15 Wheelhorse tractors .
You should be able to find a Kohler engine on that famous auction site , they do come up quite often or feel free to ask other local UK members if they can help in locating parts .
Good luck with the project & enjoy the ride