Getting married in Colombia (Bogotá)

I am thinking about getting married with my Colombian Partner. We have an 8 month old son. In all honesty , at the moment we just want a legal wedding and at a later date will renew and have a ceremony.

Can someone please tell me the easiest process, we want to do it now as we are going to apply for my partners spouse uk visa and i've heard / read its a lot smoother if you're married. we want to marry in the future but were kind of forced in a way to do the legal part now as we want to move to the uk and work for a while because of the poor opportunities here.

I have a colombian resident visa and a colombian born son if that makes the process any easier? Also I want to incorporate pre nuptual agreements, my partner has no problem with that so basically we want to sign a contract stating she isnt entitled to my assets should we seperate. Can we just write and sign our own contract for this or is there some kind of standard legal paper that needs to be signed?

anyway, any help on the matter would be greatly appreciated, i just want to know what documents we need and what we need to do?

Thanks in advance,

mike