Has your Architect done one or doesn't he know or hasn't he advised you?
The b/regs plans need to be submitted for approval - you can't start until the plans have been registered for 48 hours, but you may not want to start until the plans have been approved. You can submit these but your Architect should do as he will deal with the queries.
In the meantime, you should invite builders round to look at the site and give them copies of the b/regs plans to quote you.
Have you got any build over agreement in place with the water company?
Have you got any Party Wall Agreement in place with the neighbours?
Have you got any structural calculations for beams, timbers or ground/foundation design from a structural engineer?
Have you been advised about CDM regulations - has your Architect accepted the role of Principle Designer?