ユーレイルパス

>私は今ロンドンにいるのですが、イギリスでユーレイルパスを買うことはできますか?

できます。

>どこでいくらくらいでしょうか?(ユース料金)

まずは読んでみてください。

http://www.eurail.com/1_frequently_asked_questions#openFAQ

Can I buy a Eurail Pass in Europe?
If you are already in Europe, we can ship your Pass to you for USD 35 / AUD 44 / EUR 25.

Please note that prices in Europe are about 20% higher than outside, and not all Passes are available for sale in Europe.

The following Eurail Passes are for sale in Europe:
Eurail Global Pass
Eurail Select Pass
Eurail Austria-Croatia-Slovenia Pass
Eurail Austria-Hungary Pass
Eurail Croatia-Slovenia-Hungary Pass
Eurail Greece - Italy Pass
Eurail Hungary - Romania Pass
Eurail Croatia Pass
Eurail Greece Pass
Eurail Holland Pass
Eurail Hungary Pass
Eurail Ireland Pass
Eurail Italy Pass
Eurail Norway Pass
Eurail Portugal Pass
Eurail Romania Pass

英国のオフィスです。

http://www.eurail.com/eurail_aid_offices#uk

German Rail UK Booking Centre (Surbiton)
London
German Rail UK
Booking Centre
P.O. Box 687 A
Surbiton KT6 6 UB
Tel: 08718 808 066
Mon-Fri: 9.00 a.m. – 5.00 p.m.
Rail Europe Travel Centre
1 Regent Street
London
SW1
Weekdays: 10:00 a.m. - 6:00 p.m.
Saturdays: 10:00 a.m. - 5:00 p.m.