Hi both of you with regard the 1066 connection this event is the most investigated thing ever,all the great and good historians have given it a going over,last time I looked all the noblemen they could agree on being with William was 23 plus there men,best if you get back slowly and then if you are lucky make a connection,the mention of the 1901 census threw me abit I take it the family stayed in Essex from the 1750's,with regard going to the Essex records nothing could be more simple
it is a new building very user friendly and right next to it is a long stay carpark you will need a readers ticket all you need is a utility bill or bank statement and they will issue one on the day it's free this will allow you to look at original records.
Best Regards