As a relative newcomer too, I'd have to recommend MAD (Maldon And District) Air Rifle Club.
They are very welcoming and friendly and have a great set up. There is a plinking range with a covered area for wet days, loads of HFT targets (knock down targets in the meadows / trees etc), and they're open 24/7. There is a great informal competition every Wednesday evening in the summer. Have a look at the website and maybe pop in on Weds for a look.
All the best,
All the gear, & some