Hi Pat,
Don't bother with Skycaps, it's not cheap (see www.skycaps.com).
When you land at T5 and collect your case, go into the arrivals hall and it is well sign-posted to the other terminals, you can take the underground or the Heathrow Express trains for free travel to connect between all terminals.
Then at T3 you go to Departures and the airline check-in desk for your flight, there is usually a JY airport rep to assist you and your Tour Manager might be there - it depends on where you are going and whether the TM will already be at the arrival airport.
Because you are doing a long-haul holiday, you will also have a lounge pass, so once you are through security you can go to the lounge and meet your fellow travellers. Just look out for the JY labels on their hand luggage!
Enjoy the tour,
Sarah