Your US relatives cannot be your main sponsor. Your wife must be your main sponsor.
There are financial requirements and if your wife cannot meet these (this is usually the case where the s ponsor is NOT living in the US at time of petition) then she can have a joint sponsor; and that can be any US relative or friend.
Read the following website carefully (taken from the USCIS website) and come back with further questions.
The whole process - from the initial petition to actually obtaining the visa - takes approx 12 months.
(The London Embassy currently carried out Direct Consular filing which reduces the process to about 6 months, but this service is discontinuing this year I understand)