if your visa app is straight forward, (even if it wasn't !) i wouldn't use an agency, never have and never will, don't trust an agency to do your work, get your visa app right first time, last thing you want is the pain of a refusal and waiting for an appeal or re-applying,
it's pretty straight forward to do, everything you need to do can be found on here and not many have been refused a fiancée or spouse visa on here
