If you are planning on buying a bike at the weekend you want to ride it as soon as possible. Some companies will offer one day’s cover to ride any bike – but this will probably be expensive and if you’re young or inexperienced you might not qualify.
If you’ve got a car with comprehensive cover, you might have another option. Some comprehensive car policies also give you third party cover to drive any other vehicle – in which case it should cover you to ride the bike.
It will only be insured against third-party damage, but it may make you legal to ride home. Check with your insurer.