Go to the clubcard 'deals' on the tesco clubcard website and you will see lists of things you can cash your clubcard vouchers in for and what the value is.
This is applicable on days out, restaurants, travel etc.
Most things are "£2.50 in clubcard vouchers you cash in, you get £10 in 'deals' vouchers"
Some things you have to apply for specifically, but most things, you fill out the request on line with how much you want to cash in and the clubcard voucher code and then they send you the 'deals' vouchers (mine arrived within 2 days) and yuo just hand the 'deals' vouchers in when you pay at your cosen location.
For example, I cashed in £10 worth of cluccard vouchers and got £100 worth of deals vouchers. I used £60 worth to get into the zoo and £40 off my pizza hut bill. Just handed them to cashier, job done!
There are catches such as:
At theme parks/tourist attractions you can't use them on 'family' tickets - you have to pay for everyone individually as Adult/Child etc - which makes it slightly more expensive.
Also they can;t give change on Tesco Deals Vouchers, se best to uderpay using the voucher and the top up with cash so as not to lose anything on your voucher...make sense?!
Just spend 10 mins on there website - it's dead easy, quick and EXCELLENT value!