We were foot passengers last year and the public transport was just fantastic. If you are at Ballaugh and heading back to Douglas you will be looking for the bus that leaves from Ramsey. The bus leaves the bus station in Ramsey very soon after the road closes and will pick up at all bus stops till it reaches Lord Street Douglas.(Sea Terminal).As you can imagine these buses can be busy but they are 9 times out of 10 double decker's so there is usually plenty of room until about Union Mills or the Glenlough Campsite due to the numbers getting on. There will be a TT bus timetable on the IOM Transport website nearer the time which is also available at the Sea Terminal and at the Airport I would imagine. As you have said your staying at the Douglas Rugby Club the bus for Ramsey, Peel etc will stop very close to the entrance.