I have never used Lunbuntu but. If you have a connection when
installing, The distro will likely find the driver to use upon installation.

When installing Ubuntu on others machines I would use a Wifi dongle
known by me to work. I can see that others claim Broadcom is supported
by the kernel but I never found that to be true. Because of Ubuntu
policies proprietary drivers haven't come on the ISOs I know of. This
does not mean that drivers are not made that work well, it only means
that Ubuntu in their wisdom didn't ever want it said that they broke
copyright law in an effort to supply the masses with a free system.

I don't believe Ubuntu will ever have to cave to MS for copyright issues
as long as you have to do some of the work. This compromise is well
worth it in my book, and one of the reasons I don't consider some of the
other distros like Mint.

If you have another connection other than Wifi, an update should find
your driver for you and offer an install of said driver.