I have one of the Orange Cash cards for online purchases, that way I never have to use the one linked to my bank account.
I got one when they first came out (so it was free, it'll cost you £5 to get it now).
If the details you put in on the application can be verified you'll be allowed to load/withdraw whatever you want, if they can't (you use a made up name, they can't find you on the voters register etc) then you'll be limited to £1,600 per year.
It's a physical plastic card and can be used in shops etc, it's also wireless so can be scanned at the quick pay type machines for small amounts without having to enter your pin.
Various ways to load it, at an Orange shop is free, at any PayPoint will take £1.50 off whatever you pay in (give them £100 you get £98.50 loaded) and it's credited instantly, so if you're worried about using cards online you can load it and spend it bringing the balance back to zero within minutes.
There is also an app for it so you can see exactly what you've spent, what has been loaded and how much you have available.
Only problem I've found with it, if you don't enter the address that it is registered to correctly when you buy something it will attemp to authorise against the card, fail as the details don't match, but keep the funds as "pending" for up to a fortnight until they are restored to your account and can be spent.