Hi Jamie,
Your situation is not unusual. I subscribe to the ndg list ( see
http://lists.drogon.net/scuba-uk-ndg/) which can be used to advertise spaces, and to say you are looking for spaces.
I found it a good way to get some diving done at short notice by just making up spaces on other group trips.
Equally, the Places to fill pages here and on divernet fulfill a similar rule.
Hope you get enough diving booked ths season.
Anke