First off I'd like to thank you for using the apparently invisible edit button, it's much appreciated.
I haven't played the mod in a while but it most likely has a cap on the amount of units you can buy. I haven't done it for a while but I believe this can be changed in LondonModv1.3/specs/freeplaybase.xlm under the "Count" part.
Modded save games are absolutely dreadful and always like to go wrong, so unless you are playing in 'challenge' freeplay rather than normal freeplay it doesn't sound like something that can be fixed. Someone may have had the same issue and can offer more help.