Hi Conkarin
I think I can answer your question as a very good friend of mine used to work for a company that administered the kind of 'holiday prize' you have got.
Basically, you dont get anything in this life for free, everybody knows that....the idea is the company fly you to Spain/ Canary Islands etc, and one of the conditions of the 'prize' is that you look around a Timeshare/ Holiday owndership proprty while you are there and attend a sales meeting.
Yes typically Timeshare is very hard sell however nobody can make you buy anything if you dont want to. Legislation is a lot tougher now on the way this product is sold.
Just be aware that the holiday 'prize' will not necessary be your first choice of dates, and should you want to take additional people then extra flights are not the cheapest.
Therefore although this is not a 'prize', you have got a pretty cheap holiday for just �49.50 each..and just for taking a look around a timeshare
Dont forget should this holiday not be forthcoming then of course you have usual consumer rights and should contact trading standards
Also, refer to the T&C's on the back of the form, usually there are quite a few...!
Good Luck...let me know how you get on and hope this helps!