Dependant visa, timing and fees

Hi, my wife has just received a very interesting position in Edimburgh, but since we live in France, we of course need visas. Thing is, her firm sponsors hers (classic but still nice), but the firm her company uses for the whole legal process asks us if we want them to also take care of my and my daughter's visa.

Which would be great if they weren't asking for a 800£ management fee. Per applicant.

My question is the following:

I've seen that I can start the visa process for my daughter and I at the same time as my wife's, before hers is actually completed (just have to link with a family code apparently)

But is it that much of a hassle to do by myself, or is the 1600£ fee worth it?