Hi there,
Im a marathi, and incidentaly I live in mississauga too. Dont be alarmed not to find too many marathis around you, coz there honestly arent that many in GTA. And even if they are, they dont socialize within themselves too much, which makes them sorta isolated.
Well if you are in mississauga, you can always visit the Shri Vitthal Mandir on Matheson and Kennedy, its a marathi mandir. You can also enrol into the Marathi Bhashik Mandal.
Let me know if you need any other information.

Regards,
Kundan Joshi

Also there is a Marathi school which run classes on Saturday morning (9:45 to 12:45) for kids from Jr KG to 8th grade. If you are interested you can walk in to TL Kennady school on Hurontario and Dundas on Saturday morning about 9:30 AM.

It is supported by Peel regional board and fees are mere $20 for entire year. I found the staff very nice and my kids have shown tremendous progress in few classes. Definitely I would recommend.

Check link below from peel board
peelschools.org/parents/programs/international/register/Pages/default.aspx