Well I think the best plan to extend the network now is to install another node the same as the ECC in say St Pauls or St Werburghs. Linking the 2 together would be best done using a point to point (can to can) link with 2 Buffalos in the PCMCIA slots of the multias.
The point of leaving the node being wds meshing capable is to keep the option of being able to put in small repeaters to cover a blackspot within the local area (not for connecting different areas together)
This way each community has its own master node and a point to point link between the other community nodes, and if needed smaller wds repeaters filling in blackspots within the local area.
Hope this makes sense.
Some pricing figures:
Buffalo PCMCIA card (ebuyer) - £33.15
Buffalo pigtail (Solwise) - £7.20
Netgear ma311 card (ebuyer) - £34.41
Netgear pigtail (Solwise) - £5.83
HDF400 cable (Solwise) per M - £2.37
LMR400 cable (Solwise) per M - £2.99
HDF/LMR Ntype crimp end - £2.69
Crimping tool (Solwise) - £15.50 (maybe Santa will get me one)
Cantenna bits (RS) - £6
8db omni (Solwise) - £33