Now wishing to be rude but do try a search as a few people have used vouchers for purchases, some using them to buy other items to sell on and extract the x4 cash value of the club card points and others buying watches to keep.
To answer your question directly, there are some terms and conditions on using the vouchers but there is nothing saying you can't hand over £2k in vouchers.
Details here: http://www.tesco.com/clubcard/deals/product.aspx?R=181