Just ordered the 9ahr batteries and charger as in the original post. I'm only running wheel chair motors so think I'll be alright with those. If they drain really quick I will buy bigger packs, but only have £50 on batteries and charger at the minute.

It was mostly just to know if they were the right chemistry. If I move on to Mags or something similar in the future I'm well aware I will need more battery capacity.