Also, can I trust this wallet with hundreds of thousands of pounds ?
You can trust them as much as you would trust a third party to hold coins for you.
I'm not sure about what you're trying to say with this?
Bitcoin is about giving the power of holding
your funds back to
you. Why would you trust a third party to hold them for you, especially since you're going to buy a nice sum of coins? It makes no sense. That's what we already have, it's called a bank, and it's the reason most people end up here.
Example: would you trust me to hold your coins? If you went on holidays, would you trust me the keys to your house?
There's a saying around the forum that goes "if you don't own your keys, you don't own any Bitcoin", and that's correct (we don't even need to talk about Mt. Gox, Cryptsy, etc to verify this statement as true).
So, in short, if you don't mind losing your coins, then yes, you can trust any wallet.
You have web wallets with 2FA/SMS. Examples have been given. Use them with caution and with amount you can afford to lose. If you want to store big amounts, a cold storage method is a must have.
