Good morning Andrew,
Thanks very much for getting in touch, its great you want to try Just You, take your time to look around the forum as there are some really good comments regarding first time travel which will almost certainly put any worries to rest.
Costa de la luz is a great holiday to start with Just You, just the right amount of everything in my humble opinion, free time, chances to get out and about and a beautiful part of the world in a wonderful hotel. To date there are 31 travellers booked on this tour, with ages ranging from 44 - 87, with the average being 50.
There is also some threads within the forum which discuss age ranges etc and how age should have no bearing on travelling and that it in fact doesn't, written by travellers themselves, please see the below amongst many which I feel will be useful to you -
http://www.justyou.co.uk/forum/thread-51972.html
I do not have access to what travellers are flying from Bristol and I the lady that can tell me is away till Monday, I will let you know then,
I hope this helps,
Anything else please ask,
Kindest,
Ben