Take a look at the text of the propers for each Sunday during Lent. This should give you an idea as to the theme of the music that you should select.

There are also a number of Hymns suitable for the entire season such as:

"Lord Jesus, Think on Me" (Hymn Tune SOUTHWELL)
"Forty Days and Forty Nights" (Hymn Tune AUS DER TIEFE)
"Lord, Who Throughout These Forty Days" (Hymn Tune ST FLAVIAN)

When selecting Hymns, I always look at the propers first, then I look at the readings.

Kumbaya is written in Gullah, a creole language used by African-American people on the coastal islands off South Carolina and Georgia. The language is a difficulty. It would seem artificial for an average congregation -- typically comprised of white American suburban Catholics -- to pretend to sing in an African-American dialect. There's something very strange about it, maybe even racially insensitive.

If people want to sing a simple, repetitive religious song to encourage a contemplative attitude, get something from Taize. They're not real chant; they're not elaborate, high art, but they are written in familiar languages (you can choose among several, including English and Latin, probably Spanish too), and the texts come from Scripture and the liturgy, so there's more for people to relate to.

And, Heavens, singing any song, other than the Mass ordinary, every Sunday for six weeks would bother people.

Moreover, Kumbaya has a negative image now: people think of it as a cliche about holding hands and making shallow attempts at unity. Maybe it still has some appeal to 75-year-olds who came of age during the folk-song revival of the late 1950s.

Thanks for these thoughts. The music for Lent is set, so the next time I face into this will probably be for the Easter Season.
It is likely that we will choose one or two hymn options for entrance/offertory/communion/recessional to cover the whole of the season.
Because it is the 'family mass' which means aimed at young children, the songs I can promote would likely need to have simple tunes and words. If they could also teach some key catechetical point it would be great too.

We have started to include some taize music, which is a great step up from some other options.

anyone know of resources for singing an english setting of the ordinary to one of the traditional sets, with resources on the net for guitar accompaniment? I know this might sound awful, but as we alternate a choir with organ one week withand a singer/guitar player the next, but have to have the same music every week, if i can find the right resources I might be able to liberate the choir from ordinaries which ....well can't think of anyway to discuss them charitably. guess you know what i mean.

Any ideas welcomed.

By the way, some helpful principles for sacred music are in the first 20th century document on music, "Tra le sollecitudini" by Pope St Pius X:
http://www.adoremus.org/MotuProprio.html

For instance, sacred music must be true art. This calls on us to work with our skills and our minds, with craftsmanship. That should be enough to rule out a lot of inferior music.