I recently joined on the M100 Fibre Broadband package and i'm really not impressed so far. I'm connected through wifi playing counter strike source and i always get pings over 300 constantly. I never got this on my previously provider and ever since I joined Virgin i can hardly play any online games.
I agree with legacy1, modem mode and your own router is the way to go but as your playing on WiFi I would try it wired to your router first before trying modem mode as it will be easier and not knock everyone else off the internet in your household. Even just run an ethernet cable temporarily to test if not practical/neat to run one permanent just now.....if you run modem mode alone and no other router to test you will still need to wire it as modem mode turns off the WiFI.