Hi all,
On further looking on the "net" I have found this attached circuit. I think it has both voltage and auto charge current supply. I guess this one would give me the required 13.8v ish needed by the battery and a maximum of 1.5 amps for the charge current.
I have done some current reading on the pump concerned and there is no initial spike just a constant 0.3 A when powered by the mains volatge. The same readings were taken when connected to the two 12v batteries via the inverter, with the inverter adding 0.6 A. So the total should be 1A.