I planned a trip to Europe the month before my student visa starts but wanted to stop in the UK for 2 weeks before I continue traveling through Europe. Would I be allowed to enter the UK as a tourist for 2 weeks, leave the UK to go to France (etc.) and the enter later on my Student Visa?
This is permitted. However, if you are required to speak to a border officer when you arrive, they may be concerned that you are intending to start your studies early. You should bring with you an itinerary for your travels, and your tickets to France. In general, proof of onward travel isn't required when entering the UK as a visitor, but in your case it would be helpful, since the border officer might want some evidence that you will leave before starting your studies. There's no need to present this information unless you are asked for it.