Coinbase is one of the bigger companies so yeah you are safe when you use them.
Their prices are actually quite (fees etc.). Even for withdrawals they don't charge you the jackpot.
Even Coinfloor is a London based exchange which allows you to buy and sell in GBP and Their bank account is in Estonia, so a wire transfer or SEPA payment is still required, but you will avoid the currency exchange costs. Bitstamp accounts are in USD, but if you use the wire transfer option, rather than a SEPA payment, they will convert your GBP at very competitive rates. Be careful with SEPA payments.
