Hi Shelagh
I understand your nervousness, I remember feeling the same before my first trip but please don't worry. All airports are well signposted and there are always plenty of staff around to ask. I've travelled from airports other than London and have always found people very helpful. If in doubt - just ask for help.
Sometimes I've not been able to find the rep at Heathrow because it's so big and busy, or because I've arrived before they have, but it's been fine, I've always managed to get on the flight.
Remember to put a JY label on your suitcase and hand luggage so that other JY travellers can see it and speak to you, also please go and speak to anyone you see with a JY label, we're all in the same boat and I've never yet met anyone who hasn't been friendly.
When you get inside the terminal take a deep breath and look at the signs, you'll find it easier than you thought.
Have a lovey trip
Rose