Excel Exhibition Center holds many exhibitions and shows that are informative and entertaining.
These are the freebies that I found so far
Links and info in the first comment
Ans to Free Parking
*** Although there is parking in the centre but you will have to pay for it but we are HUKD'rs so we look for best deals so there are some restrictions free parking on the roads.
Any free parking available locally?
Yes plenty but need to drive around.
If you come from A13 and turn in A112 towards Excel Exhibition centre
1)A112 Plenty of spaces to park free bar few places -- no RPZ or yellow line
2)There are roads off A112 near a walking distance (If you have a Disabled person it is best to drop them off first) then find a space maybe up-to 10min walking distance from A13.
4) I haven't been to any other roads near A112 or the other side of EEC near West Silvertown DLR there might be similar road paring allowed. See the road marking and RPZ restriction before you park.