I love martial arts, especially Wing Chun. While practising I sometimes don't have a partner to drill the moves with. What forms can be practised without a partner?
Wing chun has forms for this purpose. There are six forms for solo training, starting with Siu Nim Tau. Keep in mind that forms are aimed at training your muscle memory, so your body gets used to the moves. Apart from this there is never enough of footwork and punching training. Once you start with Chi Sau you will need a partner. There is no way around it.
You may not believe it, but there exist studies where pure mental training had the same effects than physical training with a partner. So if you don't have a partner you can practice shadowboxing. Shadowboxing is also very advisable even if you have a partner, as it is a fundamental part of every martial art.
As already answered by user5645, this is only one side of the coin. Without a proper partner/teacher (especially for Chi-Sao) you will hardly master the style in its whole definition by your own.
But don't let this get you down, even if you can "only" train solo drills, this does not mean you can't get a good Wing Chun fighter. The great advantage with partners is that you always have some form of "feedback" ... you know if you hit the rights spot, you can "feel" your partner, ask him questions, discuss about correct angles, etc., etc.
Also partner-training has a huge philosophical part, that is, it teaches you empathy and respect for the people opposite of you. You train with a partner, but don't try to hurt him ... you together grow and get better martial artists.
A complete martial art is always about people ... life, death, love. This is also the main difference of a true martial art and MMA. MMA is sport ... it is designed to hurt people ... not to respect or love them.
So I encourage you to continue your martial art studies, even if you don't have a partner for training ... read books, watch movies/tutorials, practise forms/katas, drills, stay fit, eath healthy, respect people, pray/meditate, etc. ... everything in life is part of a true martial artisan.