To get the best deal when buying your Swiss francs, you'll need to look beyond just the exchange rates UK providers use to convert Swiss francs to pounds.
First it's vital that you have a budget in mind - in £pounds sterling - so you can compare all deals on an even footing, this budget should be sufficient enough to cover all your spending money plus emergency funds.
Once your budget is set, compare the Swiss franc conversion rates, service features and any fees and extra charges to get the best Swiss franc to pound rate for your budget, rather than simply the best advertised headline rate:

Swiss currency exchange rate

When you compare the Swiss franc exchange rates offered by different UK forex providers, check whether a minimum currency order is needed to qualify for their headline rates.
Remember, if your order wouldn't be eligible it may be given a significantly lower exchange rate Swiss franc to pound. If so, exclude the provider(s) from your Swiss travel money comparison so you're not caught out.

Minimum/maximum orders

As well as any minimum order limits linked to their exchange rates, many forex providers often set a number of other limits too.
Check that the amount you want to exchange from pounds to francs is within each provider's maximum order limit, and exclude companies who can't process your order.
Next, consider what delivery service you want and decide if you need next day delivery. Some providers charge a delivery fee while others offer it free to larger orders, so check where you stand.

Buy back guarantees

Decide if you want a buy back guarantee, letting you sell your leftover Swiss francs at the same currency exchange rate Swiss franc to pound that you were originally given.
These aren't available with all providers, but some offer it for free and others charge a flat rate fee.
If you are unlikely to have a large amount of Swiss frans left at the end of your trip a buy back guarantee may not be worth forking out extra cash for, so weigh this up before you decide.
Remember, extra charges (i.e. for delivery and/or buy back guarantees) can quickly erode even the best exchange rates available, so if extra fees are added to a deal you'll need to consider them alongside the rates quoted.
Once you've found the best rates available to your order you can compare the features of each travel money deal to find the best deal as a whole.