The Orpington and District MRS are having their annual show this weekend, just off the A21 at Junction 4 off the M25, in Pratts Bottom. This year has quite a large NG content:
Puerto Paseo On30
Glyn Valley Tramway OO9
Little Sewage Works Gn15
Little River Falls On30
Live Steam Garden Rail 16mm
In attendance you'll also find Kent Garden Railways, who also have quite an NG selection.
It's a small friendly local show.
Note: I have no commercial interest here, nor am I a member of the ODMRS, although I do know quite a few of them....