I think out of the high street banks, only Nationwide and Barclays give contactless cards.
Regardless of whether they are contactless or not, the card will only work with online card terminals. This means that it will usually work anywhere where Visa Electron cards are accepted. At peak times, some shops switch their terminals to offline mode to save time, and the card could be declined at these times.
I would stay away from paid accounts like Go Henry and Osper. They do basically the same thing as normal child bank accounts. They are also more difficult to transfer money into. If you want to pay money in, you have to set up an account with them, whereas with accounts with high street banks, you just transfer money via FPS as you would normally do.
DS currently has a NatWest Adapt account. When he reaches 18, he has the option of a Select or a Student account. I think that we will close it when he is 16 and then open a Barclays Young Person's Account, so that he has a contactless card and can set up Direct Debits and Standing Orders.
We applied online, and then had to go into branch with either his passport, birth certificate or EEA identity card, and my proof of address.
I expect him to save at least 10% of his money - the rest he can spend on sweets, electronics etc or save up for larger purchases.
I have a standing order set up for £20 each month to his account. We have relatives who live abroad so it is easier for them to transfer money to his account (using his IBAN and BIC) than sending cash for birthdays.