"Only non-European residents can use a Eurail pass." An English resident would need to get InterRail.

But see the cautions at http://en.wikipedia.org/wiki/InterRail#Decreasing_attractivi... . Going from London to Paris by train requires a 75€ supplement on ~50€/day pass. The one-way price is 123€. While there is some savings because you can go on additional trains afterwards, France also charges a supplement for InterCity trains and has a seat quota.