I don't have any fobs for the alarm, which is a bit of a worry. Is it possible to replace the alarm box from a breaking one and use those fobs ( if I could actually find one!!)

It should be just the RCL receiver and appropriately memorised keyfob's transmitter PCBs that you need to replace. The Meta alarms just respond to a signal from the RCL receiver. I don't believe that the receiver and alarm box are 'paired', but I can't be 100% certain.