The stock market also has a spread, as well as commissions. If you look at a stock price there is an ask price, which is the price the lowest seller wants for their stock, and there is a bid price, which is the price the highest buying is willing to pay for the stock. Exactly the same as what you see in your forex quotes.
The reason the spread you're paying is so high is because you trading a combination of currencies that isn't directly traded between banks. To trade GBP and CHF, a transaction is made with GBP/USD and with USD/CHF - so you are effectively paying the spread for two transactions.
If you want a lower spread, trade a pair with a lower spread, such as EUR/USD or USD/JPY.
Otherwise, just bear in mind that the crosses like GBP/CHF may have a larger spread, but the price movements they go through are relatively as large. Thus you can aim for larger profits that make up for the larger spread cost. Although you'll also need a larger stop loss, so you should trade with smaller amounts.
If you can't trade with smaller amounts, then get a different broker, or get more money.