Toddler groups and activities

Hi everyone, I have a 2.5yr old and a 16m old and we will be moving to Braintree in the new year. I was wondering if there are any groups or classes that anyone recommends that would be suitable for them. Or any other activities/playgrounds/walks etc. that we could do? I know of namcos/Freeport, notley country park, public gardens and the flitch way as I've lived in Braintree before but that was before having children was even on my radar so bit unsure of anything else! Any ideas would be greatly appreciated.