Bitcoin's stock index is exactly the same as buying physical BTC. It really can be bought at any daily exchange as long as the exchange provides payment processing that relates to you.
The best places to buy this virtual currency are Xapo, CoinBase & LocalBitcoins. Xapo is known to offer Neteller which is based in Britain. To be honest I'd much rather purchase Bitcoin than buy into an index.
if both are almost the same in concept, Then I too prefer to just buy BTC's rather than investing in something like that.