No offence but racing with an average speed of 13.5 seems a non starter.
I averaged 13.8 over 44 miles last sunday in literally evey rider going my way passed me, maybe 30 or so,
I havent even considered age group TTs yet (i am approaching 58) thinking that 60 would be a good time to start.
Its not that I am averse to being at the back, I spent years being stuffed running on the track and cross country, but so far off the pace would do me more harm than good.
Personally, I would say train hard for the next 9 months and reconsider next season, but, if that were me, I would want to be much closer to 20mph over an hour before I would consider racing