We've been asked this question numerous times. In short, yes - you can.
Fake tanning adds an additional layer on top of your skin, which actually offers additional protection against UV rays from either natural sunlight or from the use of a sun bed.
Subjecting your body to either natural sun or to the artificial rays from a sun bed will help you to lift the actual tanning of your skin. Whereas fake tanning will add a layer of tan on top of your skin. However, it's important to note that depending on the fake tan tone you have applied, you may or may not be able to see your true tan develop.
Whilst the answer is yes - you can go on a sun bed with fake tan on - our recommendation is to avoid sun beds completely due to the health risks associated. If you're choosing to enjoy the natural rays provided by the sun, be sure to wear a sensible sun tan lotion. Whilst you may achieve a more subtle tan tone, you'll protect your skin. And if you decide that you want to achieve a darker tone, you can either top up your natural tan over a period of days or weeks, or usual a gradual tanning moisturiser - like our Ultimate Gradual Fake Tan. Both will enable you to achieve the glow you want, whilst protecting your body in the process.