I don't recommend Virgin Media for 2 reasons
1. They traffic manage the upload. If you go over a certain amount during peak hours or weekends your internet is cut by 65% for 2hours. Dependant on stream settings this cap can be hit in 1-2 hours.
2. From checking google, they appear to have speed/capacity issues in W4.
One simple google check
https://www.google.co.uk/search?q=W4...hrome&ie=UTF-8
You could try putting your postcode into
http://www.superfast-openreach.co.uk/where-and-when/ to see if you can get FTTC which is available as 38 down 10 up or 76 down 20 up. The 38/10 isn't usually unlimited data. The 76/20 is.
Also it might be worth looking to see if Hyperoptic is available, Hyperoptic sell a up to 1000/1000 full fibre connection.