Hi Barry and welcome to the forum.
I dabble in a bit of perl programming both for the telecomms companies I work for, and at home.
This is all custom written for the forum, and specific to this comp which has been running a long time. The application is run on my Linux server at home - I post the html output from a database report, which is what you see on the page.
To the best of my knowledge there is no available software to run tipping comps for horse racing.
My advice is to keep meticulous hand-written records at the BBQ so you can accurately collate the data as the day goes on. If it is like any of the BBQs I've been to, the amount of grog consumed will be proportional to the number of mistakes made
I used to travel down to Ulladulla with a few mates for weekends. We put money in for each race, and drew a number. If the winning number wasn't amongst those drawn, the pool jackpotted. I tell ya, there was some enormous pools going some days, and was great fun....which is probably the main point here...make sure you have something that is fun. The serious punters will still have their bets anyway.
Good luck with it!