Can an assitant...

[munch149]

... Be as young as 16

[hectors house]

No, they have to be 17 - at 16 they could work alongside you as an unpaid volunteer but you wouldn't be able to increase the number of children you can care for until you can register them as an Assistant at 17 - and then providing Ofsted approve them and they do their first aid course you are allowed to leave them on their own with children for up to 2 hours.

Read Staff: Child Ratios in Stat Framework

3.28 - Only those aged 17 or over may be included in ratios (and staff under 17 should be supervised at all times)