I'd recommend membership very highly - and to encourage you, here are some of the posts inspired by my own activities as a member:
Crossrail's Liverpool Street archaeological dig.
An exploration of Hogarth's Chiswick - and Hogarth at the Cartoon Museum.
A walk through the Woolwich Foot Tunnel on its centenary.
City livery halls including the Vintners' Hall; Drapers' Hall; and Stationers' Hall.
The Parliamentary Archives.
A night-time visit to the Tower of London.
And a trip out of London, to Compton - home of the studio and gallery of GF Watts (founder of the Postman's Park memorial) and the amazing cemetery chapel by his wife Mary Seton Fraser Tytler.