Hello Chezzer
Sorry for the loss your husband. It is perfectly natural to be nervous and apprehensive about travelling on your own for the first time, I nearly turned back and go home again on my "maiden voyage" until that is, I thought about how much money I had paid for the holiday, that was 15 holidays ago with number 16 coming up and number 17 in my sights but not yet booked. I don't think there are many first timers who haven't been worried about taking that first step, if they weren't nervous and apprehensive then I say they were very brave people. I have been on 3 short haul and 12 long haul and never looked back so I hope this will give your some encouragement along with other peoples posts.
There has always been a good mix of ages on the holidays I have been on and regardless of age everyone has seemed to get on well, in my opinion there is no such thing as an age gap, I would add that women outnumbered men on all of my holidays.
As for flights from London, a large number of holidays are either from Heathrow or Gatwick and I always have to stop over either going or coming back due to flight times but I have come to take that as all part of the holiday, I usually book through Holiday Extras and ask if they have any "undercover" deals which seem to have worked out well, others may
have other advice that would help you.
Please give it a try, I can't guarantee it but there is usually someone else taking their first step who will be equally nervous and apprehensive as you.
Avocet